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| Illustration 1 | g00350754 |
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Fuel system schematic (typical example) | |
The fuel supply circuit is a conventional design for engines with fuel injection. The fuel supply circuit uses a fuel transfer pump to deliver fuel from the fuel tank to the electronic fuel injectors. The transfer pump is a fixed displacement gear pump.
The fuel flows from the fuel transfer pump through the cored passages of the electronic control module (ECM). This cools the module. The fuel flows then through a fuel filter before entering the fuel supply manifold. A fuel priming pump is located on the fuel filter base in order to prime the system. The system requires priming after the filter changes. The system will also require priming after draining the fuel supply and return manifolds, when the fuel injectors are replaced.
The fuel flows continuously from the fuel supply manifold through the fuel injectors. The fuel flows when either the supply or the fill port in the injector is not closed by the injector body assembly plunger. The fuel is returned to the tank by the fuel return manifold. The fuel that is not injected into the cylinder is displaced by the plunger and the fuel is returned to the tank through the fuel return manifold. Refer to the Electronic Fuel Injector for a complete explanation of the injection process.
A pressure regulating valve is at the end of the fuel return manifold. The pressure regulating valve controls the entire fuel system pressure. This provides proper filling of the fuel injectors.
The fuel system utilizes an electronically controlled mechanically actuated fuel injector in order to provide total electronic control of injection timing. The injection timing is varied in order to optimize the engine's performance. This is a result of engine operating conditions.
The engine speed is controlled by adjusting the duration of injection. The speed sensor timing ring is part of the rear gear group which provides information to the electronic control module (ECM). The signal is picked up by the engine speed/timing sensor. This information is for detection of crankshaft position and engine speed. Other information and this data allows the ECM to correctly send a signal to the injector solenoids. The fuel injector's solenoid is energized in order to begin fuel injection. The fuel injector's solenoid is de-energized in order to end fuel injection. Refer to the Electronic Fuel Injector.