VaporWorx Fuel Pump Speed Control Systems

In Part 8: How Do PWM Returnless Fuel Systems Work?, the concept of using pulse width modulation to control the speed of a fuel pump was discussed.

As a refresher, the idea is to turn the electric pump on and off very quickly so that the motor speed is sufficient to provide the needed pressure.

The length of time the pump is on is called the duty cycle. Shown in Figure 1 are some typical duty cycle waveforms:

Key Concepts:

  • Use a fuel pressure sensor for feedback.
  • As the voltage from the pressure sensor changes, so does the pump speed.
  • As the fuel pressure falls, the pump speed increases to meet the targeted setting.
  • As the fuel pressure increases, the pump speed decreases to meet the targeted setting.
  • If manifold referenced fuel pressure is needed then MAP sensor voltage can be used to provide a variety of pressure requirements.

VaporWorx manufactures a variety of controllers to perform these functions and much more.

Some examples of the types of control systems VaporWorx can provide are:

  • Simple, single fuel module PWM pump speed controllers, for example (Part Number 66136)
  • Dual OEM fuel module controllers (high-horsepower fuel delivery systems) (Part Number 66139)
  • Dual and triple aftermarket fuel pump controllers for naked pumps (automatic turn-on functions) (Part Number 66138 and Part Number 66142)
  • Piggyback controllers that allow the use of high-power modules and aftermarket pumps with OEM Fuel System Control Modules with closed loop operation. (Part Numbers 66182, 66187, 66188, 66190, and 67707)
  • Model specific controllers for engine and vehicle specific applications such as the GM LSA crate engine ECM (Part Number 66101), Pontiac G8 (Part Number 66136), and Ford Gen1-3 Coyote crate engine ECM’s (Part Numbers 66131 and 66133)

All controller kits, most of which are designated as PressureWorx or BoostWorx, contain everything needed to drive the fuel pump(s) electrically.

Different Control Strategies for OEM Fuel Modules and Aftermarket Pumps

As a way of differentiating the controllers and to help clarify the differences, an OEM fuel module and an aftermarket pump require two different control strategies.

Examples:

OEM fuel modules supported include:

  • Gen5/6 Camaro (all versions) and CTS-V3
  • Cadillac CTS-V2
  • Corvette C7
  • GM trucks originally equipped with a fuel system control module (FSCM)
  • Mustang 2004-14 S197 with OEM Fuel Pump Driver Module
  • Mustang or other 5.0L & 5.2L
  • Many others, please inquire with Aeromotive

Fuel Pumps:

  • Aeromotive TI 450 and 525LPH (F90000268 and F90000285, respectively)
  • Aeromotive Phantom, Trifecta, and many others using the TI/Walbro pumps.
  • Aeromotive Stealth 340 in single, dual, and triple pump configurations
  • DeatchWerks brushed pumps.
  • AEM brushed pumps.
  • Bosch OE and aftermarket stand-alone pumps
  • Plus many others. Please inquire with Aeromotive for suitability.


The fuel module is a larger, more complex device, but has features that no aftermarket pump, except the KPM1500, can match.

VaporWorx highly suggests using an OEM fuel module when possible due to their far superior low liquid level fuel delivery performance, long life, and all-in-one design.

Most PressureWorx and BoostWorx kits are designed to be a standalone controller, and can be operated in either constant/static or manifold referenced fuel pressure modes. To operate in constant pressure, just leave the MAP sensor components disconnected. Since there is no voltage change sensed on the MAP sensor wiring input, there is no pressure change.

A typical PWM kit for a ZL1 fuel module is shown in Photo 1.

With the use of the OEM fuel module no external filters are needed (except the GT500 Mustang), nor are any external regulators or return lines. Using the VaporWorx PWM system becomes a smart electronic fuel pressure regulation system.

The basics for connecting the VaporWorx PWM are performed as follows:

  1. Connect battery power to the PWM controller (+ and – in)
  2. Connect output power to the fuel pump using the pre-installed OE sealed Delphi connector (+ and – out)
  3. Adapt the fuel pressure sensor into a 1/8”-NPT female thread on the pressure side of the fuel system near the outlet of the fuel module. A variety of fittings are available from Aeromotive.
  4. For MAP referenced fuel pressure, install the included MAP sensor, mounting bracket, wiring, and hose. Route the hose to the intake manifold. For constant pressure applications just leave the MAP sensor components disconnected.
  5. Plug in the pre-installed OEM sealed plug into the fuel pressure sensor (where applicable, some kits do not have the pumps side terminated).
  6. Connect the three-wire wire bundle from the fuel pressure sensor to the to the PWM controller using the supplied six-cavity sealed Delphi connector.
  7. Connect the fuel pump enable wire to the ECM fuel pump turn-on circuit.

Figure 2 shows the connections outlined above:

As noted earlier, the fuel pressure sensor must be located near the outlet of the fuel module or pump. As the injectors open and close, pressure pulses are developed. The fuel pressure sensor is sensitive enough, and the VaporWorx controller reacts fast enough, to chase these pulses at idle and cruise. The length of fuel line and the column of fuel act as a pressure pulse damping system.

In extreme cases where very large pulses, or at just the right frequency + amplitude / harmonic, a Radium Engineering pulse damper may be needed.

Advantages:

  1. Very low heat generation. A minimum 50% reduction in power at idle and cruise vs. full-on systems.
  2. Longer pump life.
  3. Less electrical load.
  4. Lower noise.
  5. Simple plug-and-play design.
  6. Single fuel line, true returnless system.
  7. No return lines, filters, or external regulators for fuel module designs.
  8. Higher horsepower systems available

Disadvantages:

  1. Possible higher cost depending on components used. When all components are considered (tank, pump, control system, pump reliability, etc.) the costs often are similar.
  2. Additional wiring vs a traditional relay.

Continued Reading

This article is part 9 of the 10-part informational series: Fuel Delivery Systems – An Understanding

To continue reading in the series, use the navigation below:

Part 8 - How do PWM's Work?Part 10 - Corner Pickups & Fuel Transfer Lines