FAQ - 340 Stealth Fuel Pumps
1.) Q: Where can I find out if there is a 340 Stealth Pump for my year/make/model vehicle?
A: 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: Application Guide
2.) Q: Where can I find the installation instructions for the Aeromotive 340 Stealth Pump?
A: 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 here:
3.) Q: My vehicle year/make/model does not have a listing in the 340 Stealth Pump application guide. Which 340 Stealth Pump should I buy?
A: 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.
4.) Q: 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?
A: 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.
5.) Q: 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?
A: 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.
6.) Q: 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?
A: 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.
7.) Q: 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?
A: 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.
8.) Q: How much HP will the 340 Stealth Pump support?
A: 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 more detailed information, please see TB:501 Fuel Pumps and Horsepower here:
(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%.
9.) Q: Can the 340 Stealth Pump be used safely in e85 and how much HP will it support?
A: 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 here:
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 TB-102 here:
10.) Q: 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?
A: 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!
NOTE: For specific wiring kit recommendations, see FAQ #16.
11.) Q: I heard the 340 Stealth Pump may have reverse-polarity compared to the pump I have in my car now. What does this mean, what should I do about it, and if the fuel pump is accidently wired wrong, could it be damaged?
A: The original version of the 340 Stealth Pump, which began shipping in February 2011, had a positive/negative (+/-) orientation on the pump that was later found to be opposite factory orientation in some of the more popular applications. A change was made to the +/- position of the pins on the pump and the included pig-tail, in the fall of 2011, correcting this issue. At the same time additional updates were performed to the inlet end caps of the 11141 and 11142 pumps in order to better fit and secure the inlet filter/sock. In order to help distinguish the new version, and for enhanced cosmetic appeal, at that time the inlet end cap color was changed from white to red, so all current Stealth pumps feature inlet and outlet end caps molded in red.
In all cases, the original and the current version 340 Stealth pumps have had the correct markings for +/- (correct wiring polarity) molded into the pump’s outlet end cap, just below the pins in the plug. Simply confirming that the wire connected to the terminal marked with the + sign is the 12V hot lead from the car’s harness is all that is necessary to ensure proper electrical polarity of the motor. This is true for any 340 Stealth Pump, regardless of version.
So what if the pump was accidentally wired backwards? Since the 340 Stealth Pump employs a DC 12 Volt motor, reverse wiring is not immediately damaging to the motor, however the pump will run in the wrong (backward) direction, resulting in no positive flow or fuel pressure. Continued running of the fuel pump in this manner will eventually damage the pumping mechanism and motor shaft bushings due to lack of lubrication and cooling flow. If your fuel pump runs when power upt, but does not make flow and/or pressure, be sure to check the polarity of the wiring before running the pump repeatedly, or for extended periods of time.
12.) Q: 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?
A: 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.
13.) Q: 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?
A: 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.
14.) Q: 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?
A: 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.
15.) Q: 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?
A: 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 913-647-7300 for assistance resolving any problems and for an RGA if you wish to have your pump tested and inspected.
Sales and Tech Support: (913) 647-7300
Tech Support Email: email@example.com
Tech lines are open from 8:00 AM to 5:00 PM CST.
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