Aeromotive FourX Return-Type Fuel Control System for 3 to 4-Pump Systems (Universal; Some Adaptation May Be Required)

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, can cause pumping to effectively stop and/or induce vapor bubbles. It can happen anywhere from the pump inlet all the way into the fuel rails._x005F_x000D_

_x005F_x000D_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._x005F_x000D_

_x005F_x000D_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 the system is to vapor lock. It is very common on warm days that the fuel tank becomes so hot that it is uncomfortable to keep a hand on it._x005F_x000D_Imagine the engine in your car running at wide open throttle all the time. Stuck in traffic with the engine spinning at 6500rpm and roaring. Only a small fraction of the engine power is needed, hence, the need for a throttle. That is what Pulse Width Modulation is for fuel pumps, a power throttling mechanism._x005F_x000D_

_x005F_x000D_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(s) spins. However, there must be some kind of input/feedback to tell the electronics how to change the pump speed. The FourX uses a stand-alone MAP sensor to provide the feedback needed to control the pump speed._x005F_x000D_

_x005F_x000D_The FourX system consists of a primary and secondary PWM controller output. Under normal idle/cruise driving, the #1 and #2 pumps are on the primary side and running fast enough to provide sufficient fuel pressure. Even with both pumps running a near 30% reduction in power vs. a single full-speed pump is achieved. The #3 and #4 pumps are attached to the PWM secondary output but follow at a much lower duty cycle than the primary side. As the primary side increases in output power, so does the secondary side in a leader-follower arrangement. Since all pumps are connected through the PWM controller, they will ramp together in a smooth manner without the need for relays, Hobb’s switches, and other similar devices._x005F_x000D_

_x005F_x000D_The MAP sensor provided is a 2.5bar LSA/LS9 type. This sensor has shown to have more than adequate range for all supercharged applications. Aeromotive offers EFI pressure regulators, filters, and hoses with sufficient flowrate and pressure capacity to work well with any system. Be sure to size your fuel lines accordingly. AN8 minimum for up to 1200hp. AN10 for 1200hp._x005F_x000D_

_x005F_x000D_It is recommended that for supercharged applications that manifold referenced fuel pressure be used with the fuel pressure set to approximately 43psi at idle. This will reduce the load on the fuel pump(s) and the vehicle electrical system.

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