SPACER 3L3825 - Caterpillar

Illustration 1 g02192355
Typical fuel system schematic
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 electronic fuel injectors. The transfer pump is a fixed displacement gear pump.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 fill the system. The system must be primed after the filter changes. The system must be primed 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 that is not injected into the cylinder is returned to the tank through the fuel return manifold.A pressure regulating valve is at the end of the fuel return manifold. The pressure regulating valve controls the entire fuel system pressure. The regulation provides proper filling of the fuel injectors.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 engines performance.The timing ring is part of the rear gear group. A signal is generated by the engine speed/timing sensor. This information is for detection of crankshaft position and for engine speed. Other information and these data allow the Electronic Control Module (ECM) to send a signal to the injector solenoids. The fuel injector solenoid is energized in order to begin fuel injection. The fuel injector solenoid is de-energized in order to end fuel injection. Refer to Systems Operation, "Fuel Injector".