MOTOR GP-GEAR 3073175 - Caterpillar

Illustration 1 g00677710
Fuel system schematic (typical example)
The fuel supply circuit is a conventional design for engines that use fuel injectors. The fuel supply circuit uses a fuel transfer pump to deliver fuel from the fuel tank to the 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. Then, the fuel flows through a fuel filter before the fuel enters the fuel supply manifold. A fuel priming pump is located on the fuel filter base in order to prime the system. The fuel system requires priming if the following conditions exist:
The fuel filters are changed.
The fuel supply manifold is drained.
The fuel return manifold is drained.
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 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 Systems Operation, "Fuel Injector" for a complete explanation of the fuel 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.
Illustration 2 g00290848
Typical example of a 3508B engine
Fuel system electronic control circuit
The electronically controlled mechanically actuated fuel injector system provides total electronic control of injection timing. The injection timing is varied in order to optimize the engine's performance according to the engine operating conditions.The engine speed is controlled by adjusting the duration of injection. The timing ring is part of the rear gear group which is monitored by the engine speed/timing sensor. The engine speed/timing sensor provides information to the electronic control module (ECM). The ECM uses this information to determine the crankshaft position and the engine speed. 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 Systems Operation, "Fuel Injector".