VaporWorx ReturnX Return-Type Pulse Width Modulation Controller

High-horsepower pumping systems can create excessive heat that can lead to vapor lock. Vapor lock, a condition where the fuel somewhere in the system boils, causes fuel delivery to effectively stop. It can happen anywhere from the pump inlet all the way to the fuel rails or carburetor bowl. With pumps being about 1/3 efficient, it is understandable that all of the OEM manufacturers are using a form of speed control to slow down the pump(s) during low fuel demand conditions.

Combine high power pumps and engine heat that is returned to the fuel tank on a return type system, and the fuel tank becomes a large thermal battery. The hotter the fuel becomes, the more susceptible it becomes to vapor lock. It is common on warm days that the fuel tank becomes so hot that it becomes uncomfortable to keep a hand on it.

Large pumps like the TI Automotive 450 and 525lph pumps can take 22+ amps to drive at full power. The 450lph pump, commonly referred to as the Hellcat pump, and the 525lph, or the Demon pump, are controlled by Mopar using Pulse Width Modulation. PWM is simply turning the pump on and off thousands of times per second. The longer the electrical pulse is on, the faster the pump spins. However, there must be some kind of input/feedback to tell the electronics how to change the pump speed. Usually engine RPM, manifold absolute pressure (MAP), or throttle position sensor (TPS) feedback is used for return type fuel system speed control.

Imagine the engine in your car running at wide open throttle all the time. Stuck in traffic with the engine going 6500rpm and roaring. Only a small fraction of the engine power is actually needed, hence, the need for a throttle. That is what PWM is for fuel pumps, a power throttling mechanism.

There are no switches, relays, or Hobb’s switches needed when using the ReturnX systems. The ReturnX controller has a primary and secondary output. The primary provides sufficient pump speed to maintain fuel pressure during idle/cruise while the secondary pump follows at a lower duty cycle. This leader/follower arrangement means no relays or Hobb’s switches, just a smooth ramp-up in pump speed until both pumps are at full output.

For carbureted and EFI applications, simply attach the supplied stand-alone MAP sensor hose to a manifold vacuum source (naturally aspirated) or past the supercharger/turbocharger and make at-idle controller adjustments. The VaporWorx controller will do the rest.

A return/bypass type fuel pressure regulator is required. Aeromotive has a variety of regulators, filters, and fuel lines to meet any need.

EFI:

These systems will provide an approximate 45 – 60% reduction in power (depending on idle fuel pressure) to a TI 450lph fuel pump during idle and cruise, much lower noise, and increased pump life. For most any single pump the idle/cruise power reduction is 45-50%.

The Naturally Aspirated or Supercharged controller version should be chosen based on the engine configuration. If the controller is mis-matched to the induction type an incorrect pump speed ramp rate will occur and possibly lead to a lean condition.

If the engine makes between 0 – 10inhg ATM / 100 – 65KPA ABSthen it is not recommended to use this controller type on a naturally aspirated engine. Since the vacuum is so low there is little range for the MAP sensor to operate.

Various return type pressure regulators can be used with the ReturnX systems. Following are some guidelines:

Adjustable deadhead or full return regulators:

Standard return/bypass type regulators can be used in either constant/static or manifold referenced fuel pressure modes. It is recommended that for supercharged applications that a manifold referenced fuel pressure be used with the fuel pressure set to approximately 43psi at idle. For constant pressure systems it is best to try and keep the pressure in the 43-60psi range. The lower, the better, as long as the fuel injector has sufficient capacity. The lower the fuel pressure, the easier the pump and injectors must work. Aeromotive has a variety of regulators that will work well (LINK TO AEROMOTIVE REGULATORS https://aeromotiveinc.com/collections/fuel-regulators.

 The ReturnX Controller includes these standard features:

• Everything needed electrically to drive the fuel pump(s). No relays or Hobb’s switches needed.
• A significant reduction in the average fuel pump power requirement resulting in lower fuel temperatures and longer pump life.
• 40-80A minimum continuous power rating in a compact controller package. Total size 4”L x 2.1”W x 1-5/8”H.
• Over-temperature shutdown with automatic reset that will operate indefinitely without damage.
• Short circuit output protection that will operate indefinitely without damage.
• OEM Delphi/Aptiv connections for terminals, seals, and connector bodies.
• All cross-linked polyethylene wiring.
• UL94 rated components used throughout.
• Integrates into the OE ECM to allow all safety systems to remain functional.
• Positive and negative turn-on triggers included.
• 10-22v operating range. Can be used with voltage boosters. Lower than 10v applied to the turn on circuit will cause controller shutdown to protect from an AFR lean condition.

The basic wiring layout and connections are shown in the following diagram: