Carbureted Fuel Pumps
I’m looking at an Aeromotive EFI fuel pump for my new carbureted engine, but I need 7 PSI and your catalog (or your website) says it puts out 43 PSI, won’t this flood the engine?
It’s a common misconception for people to think that a particular fuel pump “puts out” a specific pressure. Though some pumps are pressure limited, which we’ll explain in a moment, the fact is no pump “puts out” a set pressure. What a pump does do is put out flow. And what it needs to do is put out the necessary flow, when regulated up to the required pressure needed for a particular application.
Actually, all electric pumps have a flow curve that changes with pressure. Not all companies provide flow curves for their pumps, which makes evaluating that fuel pump for a particular application virtually impossible. At Aeromotive we understand a pump’s flow curve, across a range of pressure, reveals crucial fuel pump performance characteristics, so when we quote flow, we always provide the test pressure and voltage. When you read; The A1000 flows 750 lb/hr at 45 PSI and 13.5 Volts, you’re being given vital flow data that is in the proper context. This doesn’t mean the pump “puts out” 45 PSI, rather it’s telling how much flow is available at 45 PSI. You’ll see 900 lb/hr at 8 PSI is also noted for carbureted engines.
There are basically two types of pumps used in automotive fuel systems, those that are pressure limited, for use with a static (non bypass) regulator, and those that are not pressure limited, and which must be used with a dynamic (bypass style) regulator. Pressure limited pumps are almost all intended for use with carbureted engines, and the static style carburetor regulators designed for 3-12 PSI. What happens with a pump like this is that when the flow is blocked by the regulator to prevent high pressure from flooding the carburetor, the pump bypass opens to prevent pressure from spiking and stalling the pump.
Some pressure limited pumps have an internal bypass (usually the lower flow street/strip type) that opens around 15 PSI and allows the flow from the outlet port to travel through an internal passage in the pump, back to the inlet port. The higher flow, racing specific pumps often feature an external bypass, set for 18-24 PSI. Here a return line is run from the fuel pump back to the top of the fuel tank so that when the maximum pressure is reached the excess flow returns to the tank. Either way, these pumps are not intended for use in high pressure, EFI systems, or for carbureted, boost referenced systems (blow through turbo or blower engines), even if the bypass is blocked to force pressure higher.
Many Aeromotive pumps are of the “non pressure limited” type, including the A1000 for example. This type of pump cannot be used with a static (non bypass) regulator, because to stop the flow coming from the pump completely would drive fuel pressure to 100-PSI or higher, creating excessive current draw and heat, and potentially damaging the pump permanently. Non pressure limited pumps can be operated in both low (carbureted) and high (EFI) pressure systems, as long as the proper bypass regulator is used. These types of pumps, in conjunction with bypass regulators and boost reference, are perfect choices for the high horsepower, blow through carbureted engines using centrifugal blowers or turbo chargers.
Aeromotive, adjustable bypass regulators are available to use with non pressure limited pumps that can handle flow from small to large pumps, and that can create and maintain pressure from carbureted to EFI levels. Most EFI regulators are adjustable from as low as 30 PSI to as high as 70 PSI, so those who want 43 PSI for the fuel rail and those who want 60 PSI will most probably be able to use the same pump and regulator combination. Just be sure the pump provides the necessary flow at the pressure you need.
I’m building a new carbureted engine combination, what fuel pump do I need?
New pump development is itself an exhausting process that includes prototyping and testing, then more prototyping and testing, but once we know we can deliver a pump that will meet the objective and may be moved to durability and field testing, we begin a parallel effort to develop the supporting components required to create a complete fuel system around that pump. Everything from pre and post filters to port sizes and port fittings are considered. We engineer and develop a specific regulator that will maximize efficiency of that pump, enabling the buyer to extract every possible ounce of available flow while maintaining the desired pressure. The result is a complete fuel system with specific capabilities.
What does this mean to you? It takes the guess work out of choosing the right fuel delivery, and THAT makes your life easier in a meaningful way. All you have to do is determine what pump will meet your requirements. From there the system is defined and either available under one part number or outlined with respect to the individual components you need in our easy to use “Aeromotive Power Planner”. The “Power Planner” is available in our catalog and on our website at www.aeromotiveinc.com, at the top of any page, just click on the “Power Planner” link and choose the Carbureted Power Planner with one more click.
The “Power Planner” outlines fuel systems one at a time, starting with the lowest horsepower combinations and, as you scroll down, covering applications capable of increasing levels of horsepower. The two main questions you need to answer are simply “what will the engine’s peak horsepower be?”, and “What will the fuel system require for fuel pressure?”, including base pressure and boost reference if that is required. If you’re not sure of what your engine will make power-wise, there are numerous magazines and internet forums where you can research similar combinations to the one you’re building, that have already been dyno tested, to get you solidly in the ballpark.
It’s a good idea to be somewhat optimistic when estimating horsepower, or if you prefer, build in a little head room, just to make sure you cover the bases completely. Keep in mind, all ratings provided by Aeromotive are based on flywheel horsepower. Horsepower at the tire must be corrected up to flywheel horsepower. It’s safe to allow 15% drive line losses, so you can divide wheel horsepower numbers by 0.85 to get the flywheel estimate. For example, 500 WHP divided by 0.85 equals 588 FWHP.
Every Aeromotive fuel pump is rated for horsepower capability on its product page in our catalog, and on our website. You will find several horsepower ratings that apply to various engine combinations, naturally aspirated to forced induction, and allowances are made for carbureted and fuel injected engines where a given pump is capable of doing both.
For more detailed information on how to accurately calculate fuel delivery to support horsepower, see Aeromotive Tech Bulletin Fuel Pumps and Horsepower TB-501: What to consider when selecting a fuel pump.
During hard stops or aggressive maneuvers, like after a burnout or during a road-course event, my fuel pressure falls and it takes a long time to come back up, why?
The first thing is to be certain the fuel cell or tank is full of fuel. Fuel surges forward in the tank or the fuel cell during hard braking, causing the pump to get a gulp of air. In drag racing the fuel cell should be topped off between each run. Fuel pump supply and/or pickup problems are another common cause of this dilemma. Frequently, the use of a restrictive filter before the pump, one that is too small or too fine or both, is a problem. This affects all types of electric pumps and will result in either cavitation or a loss of prime, after which the pump struggles to re-prime. Be certain the line connecting the fuel cell to the fuel pump inlet is big enough and that the inlet filter is course and free flowing. The tank or fuel cell must also have an adequate vent, otherwise vacuum builds in the tank, fighting the pump getting re-primed.
For more detailed information on potential causes of this and similar problems, see Aeromotive Tech Bulletin TB-101, TB-102 and TB-801 on our tech bulletins page.
With a newly installed fuel pump, or after disconnecting the fuel lines for maintenance, The pump does not prime or has run a long time before building pressure again.
These are symptoms of the same problems outlined in question number 3 above. Cracking the line connected to the pump inlet, then the line connected to the carburetor or fuel rail may help purge air. Briefly cycle the pump but be careful to avoid fuel leaks and prevent fire hazards when handling fuel!
At the track, from the launch to mid-track, fuel pressure is steady, but then down track, it falls 2 PSI or more, what’s wrong?
The first thing to be blamed is usually the regulator, but in fact this is a strong indication of a fuel supply problem. If for some reason there is insufficient volume available from the fuel pump to feed the engine, fuel line pressure can drop to the carburetor. Even with a static regulator, a significant drop in line pressure affects flow through the regulator, causing regulator pressure to drop. Do not automatically assume the pump is bad or inadequate, inspect and resolve any supply line issues to the pump, ensure the tank is vented and the vent is functioning, and be sure to check the fuel pump wiring, along with the overall electrical system performance. Finally, if you still have problems, contact Aeromotive for a proper flow test you can perform in the field to verify if your fuel pump is performing properly.
I’ve installed an A2000 (or A3000) Fuel pump, with the bypass from the pump connected to the fuel cell, along with a bypass regulator and return line at the carburetor. The pressure is low at the pump and adjusting the bypass regulator on the fuel pump has no affect on pressure, why?
When using a bypassing regulator at the carburetor, line pressure and regulated pressure are one-and-the-same. The bypass on the fuel pump should blocked when using a bypass regulator at the carburetor. The rule is, when two bypass regulators are connected to the same fuel pump, the regulator set for the lower pressure becomes the default regulator. A bypass regulator at the carburetor makes for an excellent fuel system, so be sure to use the recommended bypass regulator P/N’s 13202 or 13212 with fuel pump P/Ns 11202 and 11215, and install a –10 AN return line to properly control pressure.
I just installed an A2000 (or A3000) fuel pump and can’t get the regulator on the pump to go below 11-12 PSI fuel pressure. The carburetor keeps flooding, what’s wrong?
The regulator on the A-2000 fuel pump, P/N 11202, is designed to control line pressure (inlet pressure) to a static, non-bypass, Aeromotive regulator, including P/N’s 13108, 13203, 13208 and 13205. The pump bypass is not capable of flowing sufficient volume to regulate pressure below 12 psi and cannot be used alone to regulate pressure directly to a carburetor. The regulator feature on these pumps is designed to present extremely consistent, adjustable fuel pressure to the inlet of a static regulator under the hood.
I have the SS fuel pump P/N 11203 and a static regulator P/N 13205. My new engine will make more than 750 FWHP and your catalog says that’s more than the SS pump will support, unless I use a bypass regulator. Is this true, and how can a bypass regulator make that much difference?
Yes, it is true, although explaining why is somewhat more complicated. First, any electric pump flows more at a lower pressure, so more flow is available using a bypass regulator. But wait, if the carburetor runs at 7 PSI with either a static or bypass regulator, how is the pressure lower and the pump able to flow more?
At first glance, the SS pump doesn’t appear to have a bypass, like an A2000 pump for example, but in order to run a static regulator, it must, and it does have a bypass. However, the bypass in the SS pump is an internal bypass valve, meaning that when the static regulator closes to block flow to the carburetor the pressure between the pump and the regulator inlet rises until the internal bypass opens. This prevents stalling the pump and damaging the pumping mechanism. In the case of an SS pump, the internal pressure limit is 15 PSI. So, by changing to a bypass regulator that opens at 7 PSI, the flow from the pump is never stopped and the pressure to the regulator never goes above 7 PSI. The result is an increase in flow from the pump to the regulator and a higher HP limit from the same fuel pump.
Carbureted Regulators
I want to convert my EFI engine to a carburetor, how can I “knock the pressure down” coming out of my EFI pump? What Aeromotive regulator should I use for this?
A common misconception about fuel pumps is that they “put out” a specific pressure. It makes more sense to think of the pump as a source of flow. A bypass regulator creates pressure by restricting flow from the pump, forcing the pump to produce pressure up to the regulator’s set point. Once enough pressure is created the regulator bypass is forced open, allowing excess flow onto the return line. From here the regulator relieves just enough excess volume to maintain pressure. The Aeromotive 13301 bypass regulator can bypass enough volume to handle most medium to larger in-tank EFI pumps, if the return line itself is large enough. Note: Most stock EFI return lines are too small for a carburetor conversion, creating more backpressure than the regulator. At minimum, carb conversions with a 13301 regulator will require a –06 AN (3/8″) return for small OE pumps and an AN –08 (1/2″) for medium to larger pumps. When in doubt install the larger, freer flowing AN -08 line to ensure good results.
If the return line is too small, the question becomes, “Besides running a bigger return line, is there any other way to use the stock, in-tank EFI fuel pump to feed a carburetor?”
There is one possibility, but it means adding another regulator, using both a bypass and a static regulator together. In this case the 13301 regulator is used to first control what is called “line pressure”. This means feeding the stock supply line into the 13301 and then running the stock return line from the bypass port back to the tank. Next, the outlet line from the 13301 is fed into the 13205 static regulator before going to the carburetor. The 13301 is set for 12-14 PSI, high enough to allow use of the smaller, stock return line and then the 13205 is used to block that down to the 5-8 PSI range for the carburetor.
I’m using a bypass style regulator for my carbureted fuel system. I want to install a nitrous kit. How do I set up a second regulator, either static or bypass, to control nitrous fuel pressure?
To avoid engine damage, be VERY careful with this one! Adding a second bypass regulator and attempting to set it for a lower pressure than the primary bypass regulator will default the entire system to the lower pressure. Feeding a new static regulator from an existing bypass system, either before or after the bypass regulator, will not provide adequate inlet pressure to the static regulator. Understand, a dead-head regulator needs two times inlet to outlet pressure and a bypass regulator creates the same pressure at the inlet as it does the outlet. Running a static regulator for nitrous set at 5 PSI with only 7 PSI inlet pressure is a recipe for nitrous lean-out and potentially serious engine damage.
Short of installing a separate fuel system for the nitrous (highly recommended), the only reasonable option is to raise the bypass regulator pressure up to 15-25 PSI. This is enough line pressure to feed multiple static regulators, one for the carburetor and others for nitrous stages. Aeromotive now offers stackable, modular static regulators under P/N 13217 that can be bolted together for easy installation and the regulator body forms its own fuel log. Using bypass regulator P/N 11217 attached to the last stackable regulator to create line pressure necessary to feed multiple carburetors and nitrous stages. This is perfect for nitrous using inline fuel pumps like the A1000, Eliminator and Pro-Series.
No matter where I set the adjusting stud on my static (non-bypass) regulator, I can’t seem to control the fuel pressure consistently, why?
Most static carburetor regulators, including Aeromotive’s, require some flow through the unit while pressure is being adjusted. The proper procedure is to turn the pump on, start the engine and then set pressure. Steps for installing and setting a new regulator include: 1) Turn the adjustment screw counter clockwise to the lowest possible setting. 2.) Power and run the pump, with the engine off, until the bowls are full. 3.) Turn the pump off. 4.) Start the engine. 5.) Turn the pump back on. 6.) Adjust base fuel pressure up to the desired set-point by turning the set screw clockwise and locking the jam nut. Note: If you go to up and want to come down, make a small adjustment, turning the adjusting stud counter-clockwise, and then blip the throttle a couple of times to bring the pressure down.
I’m using a static (non-bypass) regulator and every once in a while the pressure spikes, going past the set point and pegging the gauge, flooding the engine. What’s wrong?
This condition is called pressure creep. It’s caused by the regulator failing to seal and stop flow when the set pressure is achieved. A static (blocking) regulator must close and stop flow perfectly to control pressure. A dead-head style pump is designed to create pressure from 14-21 PSI, in the range of 2-3 times higher than the regulator set-point. Anything that prevents the regulator valve from closing and sealing will allow it to leak, causing pressure to creep up at the needle and seat, sinking the float and flooding the engine. When pressure creep is a problem it’s common to find debris has lodged in the regulator valve. The regulator may be able to be disassembled, cleaned and restored to proper operation. In the event cleaning does not resolve the problem a rebuild kit with replacement valve will normally fix it. Aeromotive offers rebuild kits with replacement valves for all Aeromotive static pressure regulators.
My regulator doesn’t seem to keep consistent pressure, every time I look at the gauge it reads something different, it’s driving me crazy, what is the problem?
Chances are good you have a liquid filled fuel pressure gauge, infamous for changing its reading with temperature. Because a liquid filled gauge is sealed to keep the liquid inside, the pressure inside the gauge case may not be equal to atmospheric pressure. Once sealed shut, the liquid in the case expands and contracts as gauge temperature changes, making the internal pressure in the gauge vary up and down as it heats and cools. Case pressure can change as much as 7 psi up and down with heat, which affects the gauge mechanism and changes the gauge reading by the same amount!
Note: Even though the needle is moving up and down, fuel line pressure is NOT actually changing, the pressure in the gauge case just makes it look like it is. Testing for this problem is easy, just carefully heat the gauge, using a heat gun or blow dryer, from cold to warm and then hot, while running the fuel pump. The gauge reading will drop as the oil inside warms up and the pressure in the gauge case increases. Now pop the plug in the side of the gauge case and watch the pressure come back up, reading the same as before the oil was hot.
Aeromotive now offers a brand new, state of the art, Liquid Filled Fuel Pressure Gauges for carbureted and EFI engines P/N’s 15632 and 15633 respectively. These new “equalizer” gauges feature a pressure equalizing pin-valve in the side of the case allowing the user to compensate for heat related changes in case pressure, quickly restoring gauge accuracy at any operating temperature.
For more detailed information on problems with liquid filled gauges, and the new “equalizer” gauges, see Aeromotive Tech Bulletin Fuel Pressure Gauges TB-903: Liquid Filled vs. Dry, The Problem and the Solution.
What is the barb fitting in the regulator cap used for? How and where should it be connected if I use it, and what should be done with it if I don’t?
All Aeromotive, carburetor bypass regulators incorporate the necessary design to allow the regulated fuel pressure to be vacuum or boost referenced, on a 1:1 ratio. For “blow through carb”, forced induction applications, where a turbo or centrifugal supercharger pressurizes the carburetor through a hat or in an enclosure, the regulator boost port should reference to positive pressure only, not vacuum. connect the port to the carburetor box or hat, not the intake manifold. For carbureted, naturally aspirated engines, and for roots supercharged engines where the blower draws through the carburetor, the vacuum/boost reference port should be left open to atmosphere, never plugged.
There is one potential use for referencing fuel pressure to vacuum on a naturally aspirated (not blow through) carbureted engine; where alcohol is the fuel of choice. In this case a line from the regulator to the base of the carburetor, beneath the throttle blade into the intake plenum, can be used to lower idle fuel pressure and allow higher fuel pressure to feed the carburetor at wide-open-throttle.
For more detailed information on carburetion and vacuum/boost referencing fuel pressure, see Aeromotive Tech Bulletin Carbureted Fuel Pressure Regulators TB- 201: Why and how to use vacuum and boost reference.
I have a dead-head (blocking) style regulator and I want to run a return line. Will it work if I connect a return line to one of the spare outlet ports on the regulator and run it back to the tank?
No, this will not work. An open return line from one of the regulator outlet ports will render the regulator unable to properly control pressure, resulting in no pressure at idle, or at best low or no pressure at WOT under high engine load. Static regulators are normally open and designed to close when the set pressure is achieved, bypass regulators work on the opposite principle.
Pressure to a carburetor normally builds when the bowls are full and the needle shuts against the seat. An open line from an outlet port on a static regulator, running back to the tank, will prevent pressure from ever building at the carburetor needle and seat to begin with. It would be the same as taking a line from the regulator and putting it into a bucket; turn the pump on and you’ll have plenty of flow out of the line, but little or no fuel pressure to register on the gauge.
The only way a return line may be connected to a static regulator is if it is through a port blocked by a highly restrictive jet, normally something with a passage in the 0.015″-0.017″ range. This is done to allow a small amount of fuel to leak through the regulator valve to prevent pressure creep on a nitrous solenoid.
There are excellent reasons to install a proper bypass regulator for use with carbureted engines and Aeromotive has perfected this technology, offering a variety of world class bypass regulator options.
For more information on Static vs Dynamic Fuel Systems and the benefits of a bypass regulator, see Aeromotive Tech Bulletin Dynamic vs. Static Fuel Systems TB-801:EFI efficiency for carburetor fuel systems.
I have one of your Carbureted bypass regulators, advertised to adjust from 3-14 PSI. I have a blow through carb and am setting the system up for boost reference with 7 PSI at idle and 20 PSI boost. Pressure needs to hit 27 PSI with boost reference, will it work or stop at 14 PSI?
It will work perfectly, raising fuel pressure with boost on a 1:1 ratio, all the way to 27 PSI, if the pump will support it. There’s no real limit to boost reference as far as the regulator is concerned, but it’s important to understand that as fuel pressure goes higher, the flow from an electric fuel pump trends lower, and when the pump flow is no longer sufficient to support the engine’s demand for fuel at the increased pressure, fuel pressure will flatten (stop rising) and then it will roll over and start to fall if fuel demand continues to rise. This is a pump/flow problem, not a regulator issue.
EFI Fuel Pumps
I’m looking at an Aeromotive EFI fuel pump for my new engine but I need 60 PSI and your catalog (or your website) says it only puts out 43 PSI, do you have one with more pressure?
It’s a common misconception for people to think that a particular fuel pump “puts out” a specific pressure. Though some pumps are pressure limited, which we’ll explain in a moment, the fact is no pump “puts out” any pressure. What a pump does do is put out flow. And what it needs to do is put out the necessary flow when regulated up to the required pressure for a particular application.
All electric pumps have a flow curve that changes with pressure. Not all companies advertise or provide these flow curves, which can make evaluating a fuel pump for a particular application virtually impossible. At Aeromotive we understand that a pump’s flow curve across a range of pressure reveals crucial performance characteristics about any pump, so when we quote flow, we always provide the test pressure and voltage. When you read how much an A1000 flows at 43 PSI, you’re being given vital information that is in the proper context; how much flow at what pressure. This doesn’t mean the pump “puts out” 43 PSI.
There are basically two types of pumps used in automotive fuel systems, those that are pressure limited, for use with a static (non bypass) regulator, and those that are not pressure limited, and which must be used with a dynamic (bypass style) regulator. Pressure limited pumps are almost all intended for use with carbureted engines, and the static style carburetor regulators designed for 3-12 PSI. What happens with a pump like this is that when the flow is blocked by the regulator to prevent high pressure from flooding the carburetor, a bypass at the pump opens to prevent pressure from going too high at the pump.
Some pressure limited pumps have an internal bypass (usually the lower flow, street/strip type) that opens around 15 PSI and allows the flow from the outlet port to travel through an internal passage in the pump, back to the inlet port. The higher flow, racing specific pumps often feature an external bypass, set for 18-24 PSI. Here a return line is run from the fuel pump back to the top of the fuel tank so that when the maximum pressure is reached the excess flow returns to the tank. Either way, these pumps are not intended for use in high pressure, EFI systems, even if the bypass is blocked to force pressure higher.
Many Aeromotive pumps are of the “non pressure limited” type, including the A1000 for example. This type of pump cannot be used with a static (non bypass) regulator, because to stop the flow coming from the pump completely would drive fuel pressure to 100-PSI or higher, creating excessive current draw and heat, and potentially damaging the pump permanently. Non pressure limited pumps can be operated in both low (carbureted) and high (EFI) pressure systems, as long as the proper bypass regulator is used.
Aeromotive, adjustable bypass regulators are available to use with non pressure limited pumps that can handle flow from small to large pumps, and that can create and maintain pressure from carbureted to EFI levels. Most EFI regulators are adjustable from as low as 30 PSI to as high as 70 PSI, so those who want 43 PSI for the fuel rail will be able to use the same pump and regulator combination as those who want 60 PSI. Just be sure the pump provides the necessary flow at the pressure you need.
I’m building a new EFI combination, what fuel pump do I need?
Choosing the right fuel pump can seem complicated and confusing, but it doesn’t have to be. Aeromotive is an engineering company that approaches fuel delivery in a sophisticated, but surprisingly practical way. At Aeromotive we take a “pump-centric” approach to fuel delivery. This means we assess the fuel flow needs of our customers, including how much volume and at what pressure. Once we’ve established what is needed, the starting point is to engineer a fuel pump that can meet that flow and pressure requirement.
New pump development is itself an exhausting process that includes prototyping and testing, then more prototyping and testing, but once we know we can deliver a pump that will meet the objective and may be moved to durability and field testing, we begin a parallel effort to develop the supporting components required to create a complete fuel system around that pump. Everything from pre and post filters to port sizes and port fittings are considered. We also engineer and develop a specific regulator that will maximize efficiency of that pump, enabling the buyer to extract every possible ounce of available flow while maintaining the desired pressure. The result is a complete fuel system with specific capabilities.
What does this mean to you? It takes the guess work out of choosing the right fuel delivery, and THAT makes your life easier in a meaningful way. All you have to do is determine what pump will meet your requirements. From there the system is defined and either available under one part number or outlined with respect to the individual components you need in our easy to use “Aeromotive Power Planner”. The “Power Planner” is available in our catalog and on our website at www.aeromotiveinc.com, at the top of any page, just click on the “Power Planner” link and choose the EFI Power Planner with one more click.
The “Power Planner” outlines fuel systems one at a time, starting with the lowest horsepower combinations and, as you scroll down, covering applications capable of increasing levels of horsepower. The two main questions you need to answer are simply “what will the engine’s peak horsepower be?”, and “What will the fuel system require for fuel pressure?”, including base pressure and boost reference if that is required. If you’re not sure of what your engine will make power-wise, there are numerous magazines and internet forums where you can research similar combinations to the one you’re building, that have already been dyno tested, to get you solidly in the ballpark.
It’s a good idea to be somewhat optimistic when estimating horsepower, or if you prefer, build in a little head room, just to make sure you cover the bases completely. Keep in mind, all ratings provided by Aeromotive are based on flywheel horsepower. Horsepower at the tire must be corrected up to flywheel horsepower. It’s safe to allow 15% drive line losses, so you can divide advertised wheel horsepower numbers by 0.85 to get the flywheel estimate. For example, 500 WHP divided by 0.85 equals 588 FWHP.
Every Aeromotive fuel pump is rated for its horsepower capability on the specific product page found in our catalog, and on our website. You will see several horsepower ratings that apply to various engine combinations, naturally aspirated to forced induction, as well as for carbureted and fuel injected engines, where a given pump is capable of supporting flow and pressure for both.
For more detailed information on how to accurately calculate fuel delivery to support horsepower, see Aeromotive Tech Bulletin Fuel Pumps and Horsepower TB-501:What to consider when selecting a fuel pump.
After 30 minutes or so of driving, fuel pressure starts to fall, then the fuel pump gets louder and/or seems to quit running altogether. What’s wrong, is my pump going bad?
You may be experiencing EFI vapor lock. Even though the fuel is recycling through the car, eliminating localized hot spots, the recycled fuel is still being exposed to under-hood engine heat. Fuel in an EFI bypass system does slowly warm up as it is recycled through the chassis, the fuel rail(s), engine compartment, and finally back to the tank. The longer an EFI engine runs, the higher fuel tank temperatures can become. Unlike the more common carburetor vapor lock, where fuel is heated to boiling in the float bowl(s) or fuel line(s) under the hood, EFI vapor lock is often caused by hot fuel in the tank.
Excessive pump noise along with fluctuating or dropping fuel pressure often indicate that fuel temperature is high enough to cause hot fuel handling problems. A combination of high fuel temperature and low pressure can result in cavitation, where liquid fuel changes to vapor. In a return style EFI fuel system, the most likely place for these conditions to exist in the same place, at the same time, is at fuel pump inlet. Once cavitation starts, it will feed upon itself. As vapor enters the pump, it displaces liquid fuel required to lubricate the mechanism, allowing metal to touch metal, creating even more friction and heat. Once the pump begins to super heat, a complete vapor lock will develop.
In order to prevent cavitation and vapor lock, correct fuel system design and installation are vital. Ensure supply lines and inlet filters meet hi-flow, low restriction requirements and are kept clean. Keep the tank full on hot days. Reduce fuel pump speed and recycle rate with a fuel pump speed controller during low load, idle and cruise conditions. Carefully route fuel lines and plan component placement to avoid exhaust heat. Do not overlook proper tank ventilation, if the vent line or vent valve do not allow ample air to move freely in both directions, fuel delivery problems will never fully resolve. Any conditions that restrict the pump’s access to fuel in the tank must be addressed.
For more detailed information on installation issues that can result in premature cavitation, hot fuel handling problems and vapor lock, see Aeromotive Tech Bulletins TB-101, TB-102 and TB-802, all of which can be found on our tech bulletins page.
My fuel pump has been getting louder and louder, now it seems to turn on and off, or it blows the fuel pump fuse, why?
The first thing to check in this situation is the post fuel filter. Ensure it is the proper Aeromotive filter and that the element is not clogged. The post filter should be replaced at the minimum once per year in the spring, just before the driving season begins. It’s also possible your fuel pump is experiencing significant cavitation caused by conditions described in earlier FAQ’s., or it have been damage from debris. If normal steps to ensure a good installation do not resolve the issue, contact the Aeromotive Tech Support staff for assistance in diagnosing the problem and obtaining service if necessary. In the event your pump should need service or repair, an RGA is required, so be sure to call first before shipping.
For more detailed information on the importance of a clean, free flowing outlet filter, see Aeromotive Tech Bulletin Post-Pump Fuel Filtration TB-102: Selecting the correct outlet filter to protect your engine.
Why are Aeromotive fuel pumps rated for more horsepower on a naturally aspirated engine than they are for a forced induction engine?
Two factors effect an electric fuel pump’s rated ability to support horsepower, one is the max pressure the fuel pump has to produce and two is the HP consumed by any engine accessories ahead of the flywheel. Higher fuel pressures created by “boost reference” fuel systems, common to forced induction EFI engines, force electric pumps to slow down against the increasing load, reducing available fuel pump volume. A forced induction engine also requires more fuel to support HP developed in the cylinder but lost to the work required to drive the compressor helping to make the extra power.
For example, supercharged engines consume HP to drive the turbine via a belt. Turbo chargers trap exhaust heat and flow to drive the compressor, creating what are termed “pumping losses” caused by exhaust back pressure working against the piston on the exhaust stroke.
Any electric fuel pump must be de-rated for forced induction because it will support less flywheel HP. It’s interesting to note that things aren’t always what they seem; if you add back the HP lost to the compressor, the pump actually supports the same cylinder HP for forced induction as it does naturally aspirated, just less of what is developed in the cylinder remains to be measured at the flywheel.
For more information on how to accurately compensate for forced induction fuel consumption, see Aeromotive Tech Bulletin Fuel Pumps and Horsepower TB-501:What to consider when selecting a fuel pump.
I need a fuel system that can run high base fuel pressure between 70-120 PSI continuous. What Aeromotive electric fuel pump and regulator can I use?
This is a question that arises from time to time, and the first answer is; no single, Aeromotive electric fuel pump is currently suitable for continuous duty above 70 PSI. Notice I said no “single” fuel pump is suitable, we’ll expand more on that in a moment. There are several Aeromotive EFI Bypass Regulators that will support adjusting base fuel pressure in this range, including P/N 13113 for between 50-90 PSI base, as will P/N’s 13132, 13133 and 13134, with the 75-130 PSI spring installed.
The real question is what fuel pump can reliably support this high range of operating pressure while maintaining substantial fuel flow. With the exception of P/N 13134, all the regulators noted above are engineered for use with Aeromotive mechanical (belt or hex drive) fuel pumps. When operating pressures this high are required for a special application, a mechanical fuel pump is by far the best choice.
The downfall of driving a pump with an electric motor is that as pressure goes up the work load increases and the motor slows down. As the motor slows down the pump slows with it, resulting in less and less flow as pressure goes higher and higher. While it’s possible to build an electric motor that, with low voltage (12-16 volts is nothing in the world of electricity) is able to maintain high RPM at high pressure, the size and weight, not to mention excessive current draw of a motor like this, make the idea impractical at best.
A mechanical pump is driven by the engine itself, remaining small, lightweight and drawing zero current. There is a small load placed on the engine to run the pump at high pressure, but at 2-3 horsepower it’s hardly substantial compared to the engines available power. Of course, no way is the engine going to be slowed down by the pump as pressure increases, so the mechanically driven fuel pump is able to maintain high RPM at high pressure, making it extraordinarily good at producing and maintaining high flow.
Okay, mechanical pumps are best, but is it possible to use electric pumps at highly elevated pressures? Yes, but, only if we’re talking about pumps (plural). This is a special application requiring two pumps of similar flow capacity to be plumbed into the system in a specific way. This approach is referred to as plumbing “in series”. Of the two ways we can plumb multiple pumps into a single system, using pumps “in series” means one pump feeds another, with the first pump drawing from the tank and feeding the inlet of the second pump. The other approach to plumb multiple pumps is called “in parallel”, where each pump has its own draw from the tank and the outlets are joined together to a single line that then feeds the engine.
The benefit of plumbing pumps “in series” is different than plumbing them “in parallel”. Plumbing pumps “in parallel” produces a system that can deliver the combined flow of both pumps at any pressure, but don’t forget at very high pressure that may not mean much… At terminal pressure, zero times two is still zero. Parallel plumbing can be very valuable in a system requiring substantial flow but at normal pressure.
Plumbing two pumps “in series” produces a system that can deliver the same flow as one pump but at their combined pressure. In other words, two identical pumps “in series” can flow the volume of one pump but at twice the pressure. Plumbing pumps “in series” is a means of preserving flow at high pressure, working to offset the normal flow reduction due to high pressure slowing the motor. This has limited value in systems operating at normal pressures, but can prove very valuable in extreme, high pressure situations.
The technical aspect of this involves knowing how to select two pumps which, together, will accomplish the objective of supplying the necessary flow at the required pressure. We start with how much flow will be required to support the engine, and at what pressure. We then need to consult the flow curves for various pumps that may be combined “in series”, selecting pumps that would be compatible. Finally we have to know how to predict what the chosen pumps can flow at the pressure desired. The following method can predict the approximate flow available from two pumps, “in series”, at a specific pressure:
To find the flow volume available from two pumps plumbed “in series”, at a desired pressure, find the point on each pump’s flow curve where their volume is equal. Note the pressure at which this occurs for each pump. Add the two pressures together, the sum represents the pressure where that flow volume, common to both pumps, is available when they are combined and “in series”.
Combining two pumps of equal size “in series” is desirable, and makes it easy to project performance. For example, take two A1000 fuel pumps “in series”, you know they have the same flow curve (flow the same at any pressure). All we have to do is just divide the desired pressure in half and then check the A1000 flow curve. For example, if we needed 120 PSI, divide by two for 60 PSI. The A1000 flow curve shows 700 lb/hr at 60 PSI. For a forced induction engine take a BSFC of 0.65, divide the 700 lb/hr flow by 0.65 to see 1,077 flywheel horsepower (FWHP) is possible. It would be safe to expect one A1000 to support 1,000 FWHP at 60 PSI and two A1000’s plumbed “in series” to support 1,000 FWHP at 120 PSI.
WARNING: Combining pumps “in series” that have substantially different flow curves is not a good idea and will probably create more problems than it solves. For example, trying feed an A1000 with a stock fuel pump in the tank would starve and damage the A1000. A good rule of thumb to avoid problems would be to combine pumps with a differential flow of no more than 10-20%.
EFI Regulators
After installing a larger (or secondary) fuel pump for my EFI engine, the fuel rail pressure went up and my regulator won’t adjust it back down, what’s wrong?
To understand this problem, it’s helpful to think of a fuel pump as “putting out flow” instead of “putting out pressure”. A bypass regulator restricts the flow, forcing pressure up before allowing fuel to return to the tank, creating fuel pressure and then maintaining it. If pressure won’t come down as the adjusting stud is turned out (counter-clockwise), the regulator may be too small to handle the pump’s flow rate, resulting in a false pressure. Also, check the return line for kinks or obstructions and make sure it’s not too small. Remember, during normal driving (idle and cruise), the regulator and return line together must flow over 99% of the pumps volume back to the tank, without building excessive back pressure.
If the return line or the regulator, or both, are too small for the pump, the resulting fuel pressure is said to be “false-high”. This means pressure is out of the regulator’s control until the return flow is reduced, like at high engine load (WOT), when there’s less fuel on the bypass. This can cause the regulator to seem unable to be adjusted and it will create a pressure drop that looks like the pump is too small. Important: If the regulator will easily adjust 3-5 PSI lower than the desired base pressure, that’s a good indicator the regulator and return line are big enough to do the job.
Fuel is coming out of the vacuum/boost port on my regulator, why?
Fuel coming from the vacuum/boost port indicates the diaphragm has either been ruptured or delaminated (lost its coating) and fuel is passing through it. Regulator diaphragms may be damaged by service time, extreme pressures, chemical breakdown, or all of the above. In many cases the regulator may be repaired, older regulators may have to be replaced with a newer model. Service kits that include replacement diaphragms are available for all current Aeromotive regulators. Contact the Aeromotive tech department if you need help finding a service kit.
I’m trying to plumb an Aeromotive, stand-alone EFI regulator but don’t know where to put it, before or after the fuel rail(s), and which ports should go where?
Unlike a standard or “dead-head” carburetor regulator, which controls pressure between itself and the carburetor by stopping flow, the bypass regulator controls pressure between itself and the pump by bypassing flow. The optimum EFI regulator location isafterthe fuel rail(s)when possible. All pump flow, minus engine consumption, must always run to the regulator, wherever it is. Putting it after the fuel rail means all fuel must run through the fuel rail, and over the injector inlet, at all times. This ensures full flow is available to the injector in any instant. Most Aeromotive EFI regulators have two inlet ports, one on each side, and one bypass port, on the bottom. Either inlet may be used with a single fuel rail engine, both inlets with dual fuel rail engines. Any unused inlet ports must be blocked with the appropriate port plug. The ideal flow-path is: out of the fuel pump, into one end of the rail; out the other end of the rail, into the regulator side port(s); out the regulator bottom (return) port, back to the top of the tank. Dual rail applications should employ a Y-block to split the supply line before entering the rails, then individual lines are run from the opposite end of each rail into each inlet port on the regulator.
I want to connect a wet nitrous kit to my EFI engine, can I use the 1/8″ NPT fuel pressure port on my Aeromotive regulator to supply the nitrous/fuel solenoid?
Feeding nitrous from a gauge port is generally discouraged. The gauge port on most Aeromotive regulators is designed as a passage for sampling regulated pressure, and may not support adequate, regulated fuel flow for nitrous. The typical bypass EFI fuel system can be tapped anywhere between the fuel pump outlet and regulator inlet. For best fuel pressure control to the nitrous fuel solenoid, connect the nitrous fuel supply line with a “T” inserted into one of the fuel lines coming out of the fuel rail, before it goes into the regulator. This “T” should be placed as close to the regulator inlet port as possible. To feed high HP nitrous systems, consider installing a dedicated fuel system to provide the fuel flow and pressure control needed for best, safe nitrous system performance.
What is the barb fitting in the regulator cap used for? How and where should it be connected if I choose to use it, and what should I do with it if I don’t?
All Aeromotive, EFI bypass regulators incorporate the necessary design to allow the regulated fuel pressure to be vacuum/boost referenced on a 1:1 ratio with PSI. Always connect a vacuum/boost line between the intake manifold and the regulator cap for port fuel injected engines, forced induction or natural aspirated, where the fuel injector discharges into the intake manifold after the throttle body. Remember to set base fuel pressure with the vacuum/boost line disconnected from the regulator. For TBI engines or applications where the injector discharges above or before the throttle blade(s), the vacuum/boost port should be left disconnected and open to atmosphere, never blocked or plugged. Note: the ratio of 1:1 is measured in PSI. When looking at a vacuum gauge, it is normally calibrated in “HG or inches of mercury. It takes roughly 2”HG to equal 1 PSI. So, for example, when the vacuum gauge reads 10”HG, with the engine at idle, fuel pressure will drop 1/2 of that or 5 PSI.
For more detailed information on EFI regulators and vacuum/boost referencing fuel pressure, see Aeromotive Tech Bulletin EFI engines with Bypass Regulators TB- 202: Understanding and using vacuum/boost reference.
I’ve installed my new Aeromotive bypass regulator. Fuel pressure seems to adjust fine and holds great when the engine is running, but when I shut the engine off, pressure drops quickly to zero. Shouldn’t the pressure hold like it did with a stock regulator?
No, Aeromotive EFI bypass regulators may not seal perfectly when the pump is off. They are engineered for the highest possible performance when the engine is running. OEM regulators must hold pressure for 30-minutes after shut-down to pass EPA emissions standards. At Aeromotive we know our customers priority is to have the best possible flow and pressure control when the engine is running and we don’t compromise this standard to force the regulator to seal when the engine is off. If extended crank or hard-start becomes a concern, first allow the pump to run and prime as long as possible after turning the key to the run position, then start cranking the engine, just before the pump shuts off. If the priming cycle is too short to allow the engine to start easily with this approach, extend the priming cycle in the ECU if programmable, or add a timer board or momentary button to the fuel pump run circuit.
My regulator doesn’t seem to keep consistent pressure, every time I look at the gauge it reads something different, it’s driving me crazy, what is the problem?
Chances are good you have a liquid filled fuel pressure gauge, infamous for changing its reading with temperature. Because a liquid filled gauge is sealed to keep the liquid inside, the pressure inside the gauge case may not be equal to atmospheric pressure. Once sealed shut, the liquid in the case expands and contracts as gauge temperature changes, making the internal pressure in the gauge vary up and down as it heats and cools. Case pressure can change as much as 7 psi up and down with heat, which affects the gauge mechanism and changes the gauge reading by the same amount!
Note: Even though the needle is moving up and down, fuel line pressure is NOT actually changing, the pressure in the gauge case just makes it look like it is. Testing for this problem is easy, just carefully heat the gauge, using a heat gun or blow dryer, from cold to warm and then hot, while running the fuel pump. The gauge reading will drop as the oil inside warms up and the pressure in the gauge case increases. Now pop the plug in the side of the gauge case and watch the pressure drop back down.
Aeromotive now offers a brand new, state of the art, Liquid Filled Fuel Pressure Gauges for carbureted and EFI engines P/N’s 15632 and 15633 respectively. These new “equalizer” gauges feature a pressure equalizing pin-valve in the side of the case allowing the user to compensate for heat related changes in case pressure, quickly restoring gauge accuracy at any operating temperature.
For more detailed information on problems with liquid filled gauges, and the new “equalizer” gauges, see Aeromotive Tech Bulletin Fuel Pressure Gauges TB-903: Liquid Filled vs. Dry, The Problem and the Solution.
I’m transplanting an EFI engine with a “returnless” fuel rail into a street-rod. The “returnless” fuel rail on the new engine has only one fuel line connection. Do I need a bypass regulator? How should it be plumbed? Can I mount the regulator back at the tank or should it be near the engine?
Yes, A bypass regulator with return line must still be used. Locating the regulator in the rear of the car is possible, but everything works better with the regulator as close to the fuel rail inlet as possible.
In order to use the “returnless” fuel rail(s) that came on the engine from the factory, the bypass regulator must be located before the fuel rail. Since the stock returnless rails have only one connection point (the inlet), an adapter fitting for AN line is required. Aeromotive offers a number of OEM to AN adapters to help with this. The new bypass regulator should be located in the engine compartment, as close to the fuel rail inlet as possible, and the return line will be the full length of the car.
Aeromotive EFI regulators P/N 13101 and 13109 are popular for “returnless” engine transplants. Be careful using a factory style filter-regulator, like those used in the Corvette, if your fuel pump flows more than 250 LPH. The stock part is unable to handle the excess flow provided by high flow Aeromotive fuel pumps, causing false high pressure and reduced fuel pump service life. For high performance applications, most prefer to replace the stock “returnless” fuel rail with an Aeromotive Billet Fuel Rail.
I have one of your bypass regulators, I don’t want to run a return line, can I plug the bypass?
No, you must run a return line of the appropriate size, from the bypass port all the way back to the fuel tank. Why? Bypass regulators work on the opposite principle of dead-head regulators. They are normally closed, meaning the flow into the regulator cannot flow onto the bypass until the set pressure is high enough to push the poppet up against the spring and open the bypass. Once open, excess flow is returned to the tank via the return line to prevent pressure from going any higher. Blocking the return port will spike pressure to the pump’s maximum, normally at or above 100 PSI. Warning: The engine cannot run properly and the fuel pump may be permanently damaged if the regulator bypass port is blocked.
I have one of your EFI bypass regulators that is advertised to adjust from 40-70 PSI. I have a turbo and need 60 PSI base fuel pressure. The turbo will make 20 PSI boost. With boost reference, total fuel pressure needs to be 80 PSI. Will pressure stop going up at 70 PSI?
No, the regulator will raise fuel pressure with boost on a 1:1 ratio, all the way to 80 PSI and beyond, if needed and if the pump will support it. There’s no real limit to boost reference as far as the regulator is concerned, but it’s important to understand that as fuel pressure goes higher, the flow from an electric fuel pump trends lower. If pump flow falls to a point where it’s no longer enough to support the engine, fuel pressure will stop rising (flatten) and then it will roll over and start falling as fuel demand continues to increase. This type of pressure drop is the result of inadequate pump/flow, it’s not a regulator issue.
I need a fuel system that can run high base fuel pressure between 70-120 PSI continuous. What Aeromotive regulator can I use, and is there an electric pump you would recommend?
This is a question that arises from time to time, and the first answer is no. There is no single Aeromotive electric fuel pump that is currently suitable for continuous duty above 70 PSI. Notice I said no “single” fuel pump is suitable, We’ll expand on that in a moment. There are several Aeromotive EFI Bypass Regulators that will support adjusting base fuel pressure in this range, including P/N 13113 for between 50-90 PSI base, and P/N’s 13132, 13133 and 13134 with the 75-130 PSI high pressure spring installed.
The real question is what fuel pump can reliably support this high range of operating pressure while maintaining substantial fuel flow. With the exception of P/N 13134, all the regulators noted above are engineered for use with Aeromotive mechanical (belt or hex drive) fuel pumps. And, if operating pressure this high is required for a special application, the mechanical fuel pump is by far the best choice.
The downfall of driving a pump with an electric motor is that, as pressure goes up (the work load increases), the motor slows down. As the motor slows down the pump slows with it, resulting in less and less flow. Building a 12-volt electric motor capable of high RPM at high pressure is possible, but it would be so large and heavy, and draw so much current, that it would be impractical at best.
A mechanical pump on the other hand is small and light, and driven by the engine itself. Although the load placed on the engine is measurable, running a mechanical pump at high pressure draws less than 2-3 horsepower, nothing compared to the power it helps the engine produce. No way is a mechanical fuel pump going to slow the engine down as pressure increases. As a result, belt and hex drive fuel pumps can maintain high RPM at high pressure, making them perfect for high pressure, high flow applications.
So, is it possible to use electric pumps to operate at highly elevated pressures? Yes, but only if we’re talking about pumps (plural). This is a special application requiring two electric pumps of somewhat similar flow capacity, and that are plumbed into the system in an unconventional way. This plumbing approach is referred to as being “in series”. Of the two ways we can plumb multiple pumps into a single system, using pumps “in series” means one pump feeds the other, with the first pump drawing from the tank and feeding the inlet of the second pump. The other plumbing approach is called “in parallel”, where each pump has its own draw from the tank and the outlets are joined together to a single line that then feeds the engine.
The benefit of plumbing pumps “in series” is different than plumbing them “in parallel”. You could say two pumps “in parallel” will deliver twice the flow at any pressure, which can be very useful in systems with normal pressures that need substantial additional volume, but pumps in parallel at very high pressure, well zero times two is still zero. On the other hand, you could say two pumps in series can deliver the flow of a single pump but at twice the pressure. Plumbing pumps “in series” could then be viewed as a means of preserving flow, or offsetting the severe flow reduction caused by extreme pressure acting to slow the motor of a single pump down. In summary, there is limited gain running pumps in series in a system operating at normal pressure, but it can prove very valuable in applications requiring very high pressure.
The technical aspect of this involves knowing how to select pumps which, together, can get the job done, providing the needed flow at the pressure required. We must first know the flow volume required to support the engine. Then we need access to the flow curves for various pumps that may be combined “in series”. With this information we can select pumps that will be compatible. Finally, we have to understand how to predict what the chosen combination can flow at the pressure desired. The following method may be used to approximate the flow available from two pumps, “in series”, at a specific pressure:
To find the flow volume available from two pumps plumbed “in series”, at a desired pressure, find the point on each pump’s flow curve where their volume is equal. Note the pressure at which this occurs for each pump and add that together. The sum of these two pressures equals the higher pressure at which the matched flow of either pump is available from the pair, plumbed in series.
Working with two pumps of equal size is both desirable, and easy to project performance. For example, combining two A1000 fuel pumps “in series” you know that they will flow the same at any pressure. To determine flow at any pressure simply requires dividing the desired high pressure in half and looking at the A1000 flow curve for flow at that pressure. The two pumps in series will produce the flow of one A1000 at half the pressure. If the target pressure were 120 PSI, half of that is 60 PSI. The A1000 flow curve shows 766 lb/hr at 60 PSI from one pump. What would this combination support at 120 PSI? Using a forced induction BSFC of 0.65, we divide the flow at 766 lb/hr by 0.65 to find a maximum of 1,178 flywheel horsepower is possible. It would be safe to say that one A1000 pump will support 1,000 FWHP at 60 PSI and two A1000 fuel pumps, plumbed “in series” would support 1,000 FWHP at 120 PSI.
Note: Combining pumps that have substantially different flow curves is a recipe for problems. For example, thinking you could feed an A1000 with a stock fuel pump in the tank would be a mistake. If two pumps in series are not going to have the same flow rates, a differential of no more than 10-20% flow at the same pressure, between the two pumps, is likely to be practicable.
340 Stealth Fuel Pumps
Where can I find out if there is a 340 Stealth Pump for my year/make/model vehicle?
Please consult the Aeromotive Application Guide for the 340 Stealth Fuel Pump before you purchase or attempt to install one in your vehicle. There are three (3) current versions of the 340 Stealth Pump available, one of which will fit many (but not all) existing EFI applications. You can view, download, and/or print this guide directly from our website here: 340 Stealth Fuel Pump Application Guide
Where can I find the installation instructions for the Aeromotive 340 Stealth Pump?
The installation instructions are an excellent pre-purchase guide and a critical source of information necessary to correctly install and utilize the Stealth 340 Fuel Pump. Please consult them for more information prior to purchasing, and of course, for installation help, as needed. They are available on our website for viewing, download and/or printing on the associated product's page and/or on our dedicated installation instructions page.
My vehicle year/make/model does not have a listing in the 340 Stealth Pump application guide. Which 340 Stealth Pump should I buy?
If your vehicle is not listed in the Aeromotive Application Guide for 340 Stealth pumps, or the vehicle is listed but TBD is noted instead of a specific fuel pump P/N, than a direct fit version of the 340 Stealth Pump is not currently available. It is true that most any fuel pump can be made to fit into any fuel tank, given substantial modifications be made to either or both, but Aeromotive does not know or recommend what modifications would be required, or what performance level or service life would be achievable.
Purchasing and then installing a 340 Stealth Pump into vehicles that are not listed in the application guide requires unknown modifications be made to the fuel tank and possibly other fuel system components. Doing so places all responsibility for performance and service life on the purchaser/installer, in which case Aeromotive cannot guarantee a satisfactory outcome.
Even though my vehicle is not listed in the 340 Stealth Pump application guide, there is a version of this pump that is very similar to the stock pump my car was equipped with from the factory, so it should work just fine, isn’t that right?
Aeromotive has spent significant time and energy qualifying what applications are suitable for use of a 340 Stealth Fuel Pump. Although it is possible that we have overlooked a suitable application, it is more likely that we do not recommend the pump, even though its physical size may be acceptable, for other important reasons.
Attempting to install any 340 Stealth Pump in such a vehicle poses a risk, which is solely that of the purchaser/installer. Failure to make the necessary modifications to enable the pump to perform as designed may result in fuel pump or fuel system failure, which in turn could result in engine damage, and may void the factory warranty provided with each 340 Stealth Fuel Pump.
I know the 340 Stealth Pump is not available in a model recommended for my particular application, what modifications do I have to make to my car and/or my fuel system to successfully install and use a 340 Stealth Pump?
Again, nothing is impossible, any EFI pump may possibly be made to work in any vehicle application if sufficient and correct modifications are made to fit and support it. However, Aeromotive cannot recommend what specific modifications must be made for vehicles that are not listed in the 340 Stealth Pump application guide.
It’s important to understand that each OEM fuel system is carefully engineered to work as a system, consisting of a group of components, all of which are designed to work together, including tank baffling, filters, line sizes, containment modules, regulators, fuel rails, injectors and electrical power and control systems. Modifications to one part of the system may require unknown modifications to other parts of that system. Extensive knowledge of the entire OEM fuel system is required before attempting modifications to specific parts of that system.
Careful attention must be paid to all aspects of the fuel delivery system when a pump as powerful as the 340 Stealth Pump is installed. We can’t prevent someone from trying a 340 Stealth pump in any vehicle, but it is advised that one does careful research, testing, and to ensure they understand that YRMV (your results may vary), and in fact, may be unsatisfactory. In these cases, success or failure is entirely the responsibility of the purchaser/installer. Aeromotive technicians are happy to discuss unique applications, including potential pros and cons, but they cannot recommend specific modifications required for applications not listed.
My car was manufactured after 1999 and came equipped with a “return-less” fuel system, will the 340 Stealth Pump work with factory fuel systems like this?
The Aeromotive Stealth 340 Pump is typically not listed as compatible with OEM returnless fuel systems, for good reason. The advent of the “returnless” fuel system, introduced by the OEM for passenger cars in 1999, was created in response to new, more stringent EPA, EEC (evaporative emissions control) regulations which took effect in that year. That a system would be classified as “returnless” does not necessarily mean that it does not have a bypass style regulator, only that the regulator is before the engine, perhaps on the frame rail or even in the tank. In fact even the most sophisticated “returnless” systems from Ford Motor Company, where the speed of the pump is extensively varied to control pressure, have integral bypass mechanisms that promote flow through the pump’s electric motor for cooling purposes.
What is most important to understand is that today’s “returnless” systems are extensively engineered as a system and very finely balanced, including intricate confinement reservoirs in which the pump is fitted, siphon-jet pumps that are used to transfer fuel within the tank(s) and into the reservoir (and which are often fed from special ports in the OEM pump), integral remote regulators in the tank or reservoir and sophisticated electronics, all of which must work together to provide fuel tank level, fuel pump flow, and pressure, necessary to meet the factory engine’s torque and horsepower production. Of course, all of these fuel system components are engineered around the OEM pump and its flow, pressure and current draw characteristics.
Installation of a fuel pump like the 340 Stealth into today’s “returnless” systems, when you consider that it flows 2-3 times as much volume, draws 2-3 times as much current and is not necessarily the exact size and configuration of the pump it replaces, will very probably throw the OEM fuel system substantially out of balance, and if run for any length of time, may very well damage either the fuel system components or the 340 Stealth Pump itself.
Modifications can be made to the OEM “returnless” fuel system, to the various hydraulic components and electrical supply, to incorporate such a 340 Stealth Pump, and it has been done successfully and with amazing results, BUT, it truly requires re-engineering much of the OEM fuel system components and controls, and is not something the average enthusiast will be capable of handling on their own. For this reason you won’t find recommendations for the 340 Stealth pump to be used in returnless fuel systems in Aeromotive’s application guide.
My car has a “return-less” fuel system and uses a driver module to use “pulse modulation” to vary the speed of the pump, thereby controlling fuel system flow and pressure (common in, but not exclusive to, Ford vehicles including Mustangs 1999 to present). Can the 340 Stealth Pump be pulse modulated without damaging it?
Much of the answer to this question can be found in 340 Stealth FAQ #6 with respect to the “returnless” part of this question, but with specific regard to the “pulse modulation” aspect, unlike most aftermarket in-tank style pumps, the Aeromotive 340 Stealth Pump is fully compatible with aggressive speed control strategies. One of the many features that make the 340 Stealth pump unique is the “turbine” style pumping mechanism. This type of pump is much more tolerant of the aggressive type of “Pulse Modulation” method of controlling pump speed, employed by the factory engineers, to create flow and control fuel pressure.
Unlike positive displacement pumping mechanisms, “turbine” rotors are not radically affected by the inertial forces related to the aggressive starting and stopping that is caused by the low frequency pulse modulation needed to vary fuel pressure by up to 30 PSI. Aggressive pulse modulation can “cog” a conventional pumping mechanism to pieces by locking it up in both directions on a continuous basis. The Aeromotive Stealth 340 Pump features the same “turbine” style pumping mechanism used by many OEM’s in these same applications, providing potentially excellent reliability in a speed controlled fuel system which has been properly re–engineered to take advantage of the Stealth 340’s high-flow capabilities.
How much HP will the 340 Stealth Pump support?
Ordinarily, Aeromotive will publish a HP rating for fuel pumps, and we could do so for the 340 Stealth pump in the same fashion. However, the 340 Stealth Pump is typically installed in an otherwise stock, return-style EFI fuel system. For this reason various OEM components within the fuel system (engineered for a pump with only 1/3-1/2 the flow capacity of the 340 Stealth), could have a negative impact on the flow that can be delivered to the fuel rail, regardless of the new pump’s increased flow potential. This makes it difficult to project a standardized HP limit for the 340 Stealth Pump that would be correct across the many applications in which the pumps may be used. Bottom line, fuel system combinations and variations from one vehicle to the next, across the wide range of year/make/models listed in the application guide, are just too numerous to properly calculate maximum HP for each.
One thing you can be certain of, the 340 Stealth Pump you receive has been thoroughly flow tested and verified to meet all specs across the full range of pressure, and to be at or below the spec current draw. All 340 Stealth Pumps are tested multiple times in production to ensure each individual pump does flow 340 lph and meets all quality and performance specs, 100%.
So, putting aside all the variables, let’s presume the best case scenario: What maximum HP could a 340 Stealth pump support if the system were fully optimized?
Okay, in a bypass EFI fuel system that has been optimized to include:
- a 72 lb/hr injector (presuming V-8 engines, 150 lb/hr for 4 cylinder engines)
- 40 PSI base fuel pressure, vacuum line disconnected
- Boost is limited to 20 PSI (allowing a 1:1 boost reference to 60 PSI max under load)
- Providing the system has the necessary electrical supply to properly power the pump
- An appropriate fuel line size equivalent to AN-06 is installed
- A high-flow filter such as Aeromotive 12301 is installed
- A decent, high flow fuel rail is employed to feed the injectors
- A high flow regulator such as P/N 13109 and a AN-06 return line is present
It would be reasonable to rate the 340 Stealth to 700 flywheel HP EFI forced induction, 900 flywheel HP EFI naturally aspirated, on gasoline fuel. In this example the injector duty cycle for either V-8 or 4-Cyl would be between 80-85%.
For carbureted engines, with optimized fuel system components including a Aeromotive P/N 13204 Carbureted bypass regulator and AN-08 or ½” return line, it would be safe to allow for 900 HP forced induction (blow-through) and 1,100 HP naturally aspirated limit
Remember, these projected HP capabilities for the 340 Stealth Pump are based on gasoline as the fuel and are 100% dependant on all aspects of the fuel system being modified if needed/as necessary to allow it to deliver full capacity to the fuel rail or carburetor float bowl(s). Aeromotive provides extensive technical information about how to accurately determine the correct fuel pump for any application in the Tech Bulletin Section of our website.
For detailed information, please see Aeromotive Tech Bulletin Fuel Pumps and Horsepower TB-501:What to consider when selecting a fuel pump.
(Note: 1 lph is roughly equal to 1.6 lb/hr if you wish to convert lph to lb/hr for calculations.)
WARNING: In a stock EFI fuel system where the pump is installed with minimum changes, it would be wise to de-rate the optimized capacity of the 340 Stealth pump by up to 10-20%.
Can the 340 Stealth Pump be used safely in e85 and how much HP will it support?
E85 fuel has become a viable option for street performance enthusiasts in recent years. It has some very significant pros, and equally significant cons, to consider. It does provide higher octane, and lower charge air temperatures, and is especially popular in forced induction applications, permitting more aggressive combinations of boost, compression ratios and tuning. It is also less costly per-gallon than high-octane racing gasoline. That said, fuel usage increases 30-35% to support equal HP, somewhat offsetting the lower cost and requiring the HP rating of all fuel system components, including and especially the HP ratings of the fuel pump and fuel injectors, be reduced by 30-35%.
A crucial consideration regarding whether or not to run E85 is its tendency to rapidly and frequently contaminate and clog/block fuel filters, resulting in significant flow restrictions, which in turn may damage the engine and/or cause premature fuel pump failure. The reasons for filter contamination problems with E85 include:
- E85 is an alcohol based fuel, and alcohols are hygroscopic (attract and absorb water from the atmosphere), which can accumulate in and clog fine filter elements.
- E85 is an agriculturally produced fuel and, being a byproduct of plant material, there have been indications some of this “bio-mass” can accumulate in, and clog fuel filters.
- E85 has very strong solvent properties, like many alcohol based liquids, which will act to strip accumulated debris and residues from transport and storage containers, and the inside of fuel tanks and fuel lines, which in turn accumulate in, and clog fuel filters.
Aeromotive has conducted extensive testing of the 340 Stealth Pump in E85 fuel, achieving 1,000 plus run hours of service life operating at 60 PSI and 13.5 Volts. In testing, it was found a filter service interval that gave good fuel pump service life required a new, down-stream filter be installed every 10 run-hours. It is vital to understand that a blocked filter creates severe flow restriction of pump output, building excessively high operating pressure between the pump and the contaminated element. If the Stealth 340 is allowed to run in this environment, operating pressures between pump and filter can exceed 90 PSI, creating extreme current draw and reduced cooling flow, resulting in rapid failure of the fuel pump motor assembly.
WARNING: If you plan to run E85 fuel you must be prepared to install proper filtration, and maintain it as frequently as every 10 run-hours. If not, Aeromotive does NOT recommend you the use of E85 with the 340 Stealth Fuel Pump. Aeromotive’s new product warranty assures the purchaser their 340 Stealth Pump will be free from defects in material and workmanship for one year from the date of purchase. Fuel pump failure caused by clogged/blocked fuel filters is not the result of any defect in the pump itself, and is not covered under this warranty.
For a detailed look at post-pump filter options and what a good one should be like, please see Aeromotive Tech Bulletin Post-Pump Fuel Filtration TB-102: Selecting the correct outlet filter to protect your engine.
For a specific example of the issues related to a clogged post-pump filter, please take a moment to see the Case History File embedded in Aeromotive Tech Bulletin Post-Pump Fuel Filtration TB-102: Selecting the correct outlet filter to protect your engine.
I heard that to use the 340 Stealth Pump you have to upgrade the OEM factory fuel pump wiring, and possibly the relay and fuse/breaker, is this true and why?
The wiring used to power the fuel pump plays a key role in supporting the electric motor that runs the pumping mechanism. It’s the combination of motor torque and the pumping mechanism speed it produces that enable the incredible flow the Stealth 340 is known for. The factory fuel pump wiring and electrical components were engineered for a fuel pump drawing ¼ to ½ the current. Failure to upgrade this wiring, including the relay and breaker/fuse assembly, may result in a substantial reduction in performance of the new 340 Stealth.
The 340 Stealth Fuel Pump is a break-through in OEM replacement fuel pump technology. It is capable of flowing 33% more than conventional, performance replacement fuel pumps, and as much as 100%-300% more than the vehicles original pump. For proper installation and to ensure the optimum performance and service life, please see the installation instructions on page 2 to view the flow and current draw at pressure chart, and the bottom of page 3 for wiring recommendations. Ensure proper wiring, your new 340 Pump, and your engine, depend on it!
I plan on installing a 340 Stealth Pump as part of a completely new, EFI fuel system. Starting from scratch, what fuel lines, filter, and regulator is recommended?
The optimum EFI fuel system for a 340 Stealth Fuel Pump, necessary to assure the full capacity of the pump may be delivered to the engine, would include the following:
- A baffled fuel tank with a minimum 1.5 gallon internal sump capacity
- HD electrical bulkheads to pass power and ground through the tank or top-hat
- AN-06 or 3/8” fuel line, supply and return, with the return into the internal sump
- A suitable, high-flow fuel filter such as Aeromotive P/N 12301 before the engine
- A quality, high-flow fuel rail assembly with AN-06 or larger ports on all four ends
- A high flow, triple AN-06 Y-block to feed each fuel rail for V-8 engines
- A high-flow, boost reference EFI regulator P/N 13109 after the fuel rail(s)
- Substantial electrical supply, like P/N 16301 HD wiring kit or P/N 16306 FPSC.
I have an aftermarket top-hat/hanger assembly for multiple, stock-style in-tank pumps. I’d like to use several 340 Stealth Pumps with this hanger, will it work okay?
Using multiple 340 Stealth fuel pumps should practically be limited to 2-pump hanger assemblies. With a combined flow from just 2 pumps of 680 lph (over 1,000 lb/hr), at 43 PSI and 13.5 volts, there are few OEM fuel tanks with adequate baffled area to feed this much volume for anything more than short bursts of full engine power. WARNING: Fuel tanks with no, or an insufficiently sized baffled area to maintain fuel pickup, may experience dangerous high-load lean-out problems, especially when the tank is ½ full or lower.
Considering the wiring requirements for a single 340 Stealth pulp, installing multiple pumps on a single hanger will require serious, heavy duty electrical bulkheads, along with the same level of external wiring, relay(s) and fuses/breakers. Looking at the flow and current draw chart on page 2 of the 340 Stealth Pump instructions, you see that each pump is drawing 15 amps at 60 PSI and 13.5 Volts. Two pumps draw 30 amps, 3 pumps 45 amps. As pressures go higher, so goes current draw, with a peak of 19 amps per pump at 90 PSI pressure.
If the fuel flow requirement to adequately support the engine exceeds what 2-340 Stealth Pumps can provide, Aeromotive recommends the installation of a larger, single pump such as the Eliminator, or in extreme applications, the Pro-Series pump.
I know the 340 Stealth Pump is used for high-pressure EFI engines but my engine is carbureted, is there any way I can use one too? If so, what regulator would I need and how should I plumb the fuel system?
Contrary to what most people think, pumps don’t necessarily pump pressure, what they do pump is flow. Now, some pumps flow more at higher pressures than do others, which is what separates a high pressure EFI pump from a low pressure carbureted pump. That said, there’s nothing to say you can’t run a pump capable of EFI pressure at carbureted pressure levels.
What is required for all pumps capable of high pressure is the use of some form of external, bypass regulator (high pressure pumps have no internal bypass and cannot be run with dead-head or blocking style regulators). To use the 340 Stealth pump for a carbureted engine is not only possible, these little in-tank pumps can be part of a very effective carbureted fuel system, capable of both high horsepower and quiet, continuous duty street operation.
The secret to success with the 340 Stealth Pump and carbureted engines is to select the proper carbureted bypass regulator, Aeromotive recommends P/N 13204, and to install a large enough return line, ½” or AN-08 from the regulator back into the top of the fuel tank, in order for the regulator to work properly. Note: the OEM EFI top hat and return connection are too small for carbureted applications regardless of the return line size used. You must increase the connection for the return line in the top of the tank to ½” or AN-08 as well.
I purchased and installed a 340 Stealth Pump and It appears that the pump is either not turning on and pumping fuel/making pressure, or it is underperforming when the engine goes under load. Could it be defective? What can I do to solve the problem?
Although anything is possible, Aeromotive goes to great lengths to ensure the product you received is thoroughly and completely tested before it goes into the box. Every single 340 Stealth pump is fully and individually tested for flow, pressure and current draw, using the same test procedures, and on the same flow-test-bench we use to verify the performance of every A750, A1000, Eliminator and Pro-Pump we build. No fuel pump at this level receives more thorough attention in the build and testing phases than the 340 Stealth Pump does.
Of course, it is possible that something happened to the pump prior to installation that is creating a problem, however, 99% of the time, function and performance problems in the field are installation related. Aeromotive is of course happy to re-test any Stealth 340 pump, at any time, and we do not charge for testing, performance verification, or warranty inspection.
If your fuel pump is not operating correctly, or fails to perform to expectations once it has been installed, we recommended the following steps for trouble shooting the installation:
1.) Review the 340 Stealth Pump application guide and installation instructions to determine the pump is suitable for your vehicle and is correctly installed.
2.) Ensure wiring is adequate and the connection polarity is correct to run the pump at the designed speed and in the correct rotating direction.
3.) Verify the vapor purge port on the inlet end of the pump (see page 3 of the installation instructions for more details) is not blocked or obstructed.
4.) Ensure the filter is both capable of flowing with the pump and is free from debris and/or blockage that would reduce flow to the engine and/or damage the pump.
5.) Contact the Aeromotive Tech Department for assistance and for issuance of a Return Goods Authorization (RGA) if required.
NOTE: The warranty provided by Aeromotive is factory direct, and requires you return the pump to the Aeromotive directly, NOT to the point of purchase, for warranty consideration. Please contact the Aeromotive Tech Dept at 913-808-2376 for assistance resolving any problems and for an RGA if you wish to have your pump tested and inspected.
Brushless Fuel Pumps
How do brushless Aeromotive pumps compare in size to their brush-style counterparts?
Aeromotive brushless pumps have similar dimensions and port sizes to their equivalent brush style pumps, but may have offset inlet/outlet ports compared to the centered inlet and outlet ports on a brush pump.
Also, the mounting-hole dimensions are typically similar in width but may be closer together compared to the longer sleeve on the companion brush-style pumps. Overall packaging dimensions are similar enough however to avoid major rework for mounting space and line connections.
Can Aeromotive brushless pumps handle ethanol and methanol fuels?
Aeromotive Brushless pumps feature outstanding cross-fuel compatibility and can handle most fuels from pump gas to av-gas to jet fuel, diesel fuel, ethanol up to E98, and methanol fuels. They are not compatible with Nitromethane.
How much HP will a Brushless Pump support on gas/diesel/ethanol/methanol fuel?
In practically all cases Aeromotive will provide conservative, gasoline FWHP (flywheel HP) estimates for all fuel pumps we manufacture. In many cases, there may be additional HP ratings for other fuels. All of our published ratings can be found on the product specific page for that particular pump on our website.
As a practical exercise, you may simply take the listed HP rating for gas on any fuel pump you’re
interested in from the appropriate product page and simply calculate the limit for an alternative fuel as follows:
From gas to E85 take the appropriate gas HP rating and multiply by 0.7.
e.g. 1000 FWHP gas x 0.7 = 700 FWHP E85
From E85 to Methanol take the above E85 HP rating and multiply by 0.5.
e.g. 700 FWHP E85 = 350 FWHP Meth
From gas to Methanol directly multiply the gas HP rating by 0.35.
e.g. 1000 FWHP gas x 0.35 = 350 FWHP Meth
Gasoline to diesel ratios are pretty much the same, so figure 1:1 or no offset/penalty for diesel fuel.
If you’re a number cruncher or you just want to dig more deeply into the topic, there’s also a Tech
Bulletin on our website: Fuel Pumps and Horsepower TB-501 : What to consider when selecting a fuel pump. This detailed Tech Bulletin will explain how to calculate fuel requirements for the various fuels and with respect to the various naturally aspirated, nitrous, and forced induction applications.
Do you have a Stealth Brushless Fuel Pump for Mustang/Camaro/Corvette Stealth Tanks?
Currently, due to packaging/fitment challenges, Aeromotive Brushless Pumps are not yet configured for the very tight confines of an OEM fuel tank installation like those of the Mustang, Camaro, and Corvette stock tanks. There are Stealth (in-tank) versions of the Brushless pumps available for our aluminum Stealth Fuel Cells, and for use in custom-built/fabricated fuel tanks, but that’s the limit of the Stealth Brushless pump options at this time.
Can I use the PWM output from my ECU to vary the speed of a Brushless Aeromotive Fuel Pump?
The short answer to this question is no, you can’t use the ECU’s PWM output to control a brushless fuel pump’s speed. That said, all brushless Aeromotive Fuel Pumps are now available with an optional TVS (True Variable Speed) motor controller installed from the factory. Brushless motors are the state of the art in electric motor development, but they are quite different from the venerable brush style motors we’re used to working with.
Unlike brush-style motors, a brushless motor is technically a 3-Phase AC motor, so a direct DC power supply will not run the motor. Instead, a brushless motor requires the DC input power be processed through an inverter, equipped with a processor, to create and manage the necessary 3-phase output pulses required to get the brushless motor running and keep it running. This component, simply called the motor controller, is included with all Aeromotive brushless pumps.
Unfortunately, providing a pulse modulate DC power supply to a brushless motor controller cannot control the 3-phase output to the motor, will not vary the pump speed, and can only upset, and quite possibly damage, the onboard brushless motor controller’s built-in inverter and processor. This is where the Aeromotive TVS (True Variable Speed) controller comes into play. By providing a simple 0-5 Volt DC signal on a 3rd, yellow input wire built into the pump’s motor controller, like that from an existing TPS sensor, a dedicated map sensor, even a mass airflow sensor, the pump speed can automatically be regulated by engine demand.
What other means are there to control the speed of an Aeromotive Brushless TVS enabled Pump?
Controlling the speed of a Brushless Aeromotive Fuel Pump may only be done in conjunction with an Aeromotive Brushless Pump Controller with TVS (True Variable Speed) built-in. There are a number of ways to manipulate the TVS control wire, creating a multi-step speed change or a smooth, variable speed change. Some of these wiring options are explained in each fuel pump’s installation instructions, available on our website's products page or on our dedicated installation instructions page.
If you would like to explore other options feel free to contact the Aeromotive Tech Department by phone at 913-647-7300, ask for “Tech”, or by email at tech@aeromotiveinc.com. Keep in mind these discussions can get technical and are far easier to have in conversation as opposed to via email.
What’s wrong with my Brushless pump, it makes strange noises when I turn it on, or it doesn’t turn on right away, or seems to start and come up to speed slower than my brush style pump when power is applied?
The Start-up sequence on a brushless motor is totally different than a conventional brush-style motor and can be disconcerting to those who’ve never experienced it before. Because there’s no contact between the rotor and the stator the brushless motor controller/computer must first run a sequence of pulses to locate the stator position before the startup pulses can be generated in the correct sequence. The result is a process that may include audible beeps or clicks followed by a sweeping motor start-up that progresses the motor from a dead stop to full speed.
Can I stage a Brushless pump, in other words, can I activate it with a Hobbs switch or programmable output, where the stock in-tank pump runs continuous and the brushless pump only runs at high engine load?
Due to the start-up sequence that occurs when a brushless motor receives power and the somewhat delayed time required to get the pump up to full speed it is generally not recommended to run a Brushless fuel pump as the second pump in a staged system. Better to run the brushless pump with TVS controller as the primary and stage a brush style pump to turn on for additional flow when needed than the other way around.
It is possible to run a Brushless TVS controlled pump continuously, along with a primary in-tank pump, but at full slow speed and, using either the TPS sensor or, if boost control of the larger pump is desired, a MAP sensor could be used to bring the second, larger pump up to full speed without any concern for startup time.
Why do I need 6-gauge / 4-gauge wire for my 7/10 GPM Brushless pump when the wires coming out of the pump are so much smaller, and how do I connect them together?
It can be disconcerting when you see the difference in the wire sizes recommended to feed the pump compared to the wires coming from the pump, but as you can imagine, there’s a good reason why. Without getting too wonky, wires are like tubing or pipes only they flow electrons instead of fuel or air, and the proper size wire size or gauge, or tubing or pipe diameter for liquid or air flow, is calculated against the volume of flow required over the length. So, the longer the length, the bigger the wire or tubing for a given flow volume. The wires on the pump are a special grade, low resistance wire, and for their length are adequate in gauge, but the longer wires that go to the pump, which are of a lesser quality as well, need to be commensurately larger to carry the current (electrons) without a voltage (pressure) drop to the pump.
As for making the connection, there are butt-splice adapters that can be used that have the appropriate wire gauge reduction built-in, but the best way is with a 4-terminal junction block with two paired groups of common terminals. This would allow the large wire for power or ground to be fitted with the proper ring terminal to connect to one side of the junction block lugs and the matching pump wire (power or ground) fitted with a same size ring terminal but for the smaller gauge wire and attached to the other side of the matching terminal block. This way you have a solid connection that won't drop voltage and either the harness or the pump can be easily disconnected and/or reconnected with no problem.
My Brushless Pump was working fine but now the wiring gets hot and/or the fuse/breaker is blowing, why?
Aeromotive’s new line of brushless electric pumps, particularly the Gear Pumps in the 5, 7, and 10 GPM range, are moving far more fuel than any previous electric pumps commonly available to racers. This can place serious, unexpected demands on plumbing, filtration, and wiring. The 7 and 10 GPM pumps require 6-gauge power and ground supply wires, and a relay and breaker rated for 60-80 plus amps continuous. Filters, especially post-filters, need to have not only the right size ports but ample surface area to handle the flow and the typical debris found in more corrosive Ethanol and methanol fuels while retaining sufficient flow capacity.
Probably the most common cause for hot wires and tripped breakers/burned fuses is a combination of under-wiring and the use of a post-filter that is either too small or loaded with debris and creating significant back pressure, which in turn creates significant, unnecessary high pressure and corresponding, excessive current draw.
There are several Tech Bulletins on our website on filtration, pre-filters (Pre-Pump Fuel Filtration TB-101: Selecting the correct inlet fuel filter to protect your pump), and post-filters (Post-Pump Fuel Filtration TB-102: Selecting the correct outlet filter to protect your engine). We also have a detailed case-history example on post-filtration issues, and they’re worth checking out. If you’re having this problem, simply remove the post-filter and run the pump, if the wires stay cool and or the fuse doesn’t blow running the pump in the pits, that’s a pretty good sign you’ve found the problem.
Why does the post-filter element in my fuel system with a Brushless Gear Pump look all smashed?
Because it clogged up to the point the pressure building on the outside of the element was so much higher than the pressure on the inside of the element (the pressure produced by the pump to push through the clogged element became much higher than the pressure in the fuel rail after the filter) that the structure including the support wire inside the element could no longer keep the element round.
When this happens it can both lean the engine out and damage the fuel pump. It’s critical to have the correct sized filters in a high flow fuel system to minimize restriction, and to maintain those filters as required to keep the system flowing as freely as possible. There are several Tech Bulletins on our website addressing post-filters (Post-Pump Fuel Filtration TB-102: Selecting the correct outlet filter to protect your engine), including a detailed case-history file example of what happens with things go wrong that are well worth checking out.
How much pressure does your Brushless Pump push?
The idea that a pump “puts out” pressure is a common misconception that causes a lot of confused thinking when it comes to fuel pumps and fuel delivery. While it’s true that some pumps are pressure limited, meaning they have an internal or external bypass that will limit the pressure they “put out” when running against a dead-head or blocking style regulator, most pumps that can be run with fuel injection have no effective bypass or pressure limiting valve.
While most good electric pumps may have a maximum pressure where the pump stalls, that’s usually well above any normal operating pressure, upwards of 100-PSI plus, so they will put out whatever pressure the bypass regulator is set to open and bypass. The pressure any pump puts out is determined by the bypass pressure setting, you can make your inline pump run from 3-PSI to 73-PSI, whether it’s an A750 pump or a Brushless 10-GPM pump, as long as you have the correct bypass regulator fitted with a properly sized return line returning fuel back to the tank.
