The PCM uses the fuel pump control module to electronically maintain the desired fuel pressure in the fuel rail. It just has a high-tech twist on achieving that goal, when compared to its older brother. It’s a system with a simple goal: maintain pressure in the fuel rail. The fuel pump relay is now toggled by the ignition switch. One notable change however, is the PCM no longer controls the fuel pump relay. One Ford-specific component that still remains after more than two decades is the inertia fuel cut-off switch. A couple of things that become optional across other makes that Ford still includes are the fuel pump relay and the in-line fuel filter. This much should remain the same for any electronic returnless system. This system consists of a rotary vane fuel pump (same as before), fuel line (pressure only), fuel rail pressure sensor (that also contains a temperature sensor), fuel pump control module and, of course, the PCM. With an electronic returnless system, the PCM can now raise or lower fuel pressure at will. Also, making it electronically pressure controlled gives the PCM more flexibility over fuel control by adding another option if needed.

That’s the idea of the new system no return line to send extra heat energy to the tank.Īs an additional benefit, a returnless system, having one less fuel line, reduces the chances of a fuel leak. Naturally, the heated fuel would vaporize in the tank at a higher rate than if it were kept cool. With the older return type fuel system, the fuel would be pumped up into a hot fuel rail overtop of a hot engine, and the fuel would return to the tank full of heat energy. Well, actually, the main idea is to reduce fuel vaporization back in the fuel tank. Now, we need to make that all fancy by adding a new controller, adding a new sensor and speeding up and slowing down the fuel pump to control pressure.What sense does that make? Are they just trying to sell new parts and tools or what? A simple electric pump pushing fuel up to the engine, with its pressure being controlled by a little valve, and returning the unused fuel to the tank was not good enough.

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