Fuel Pump: Description and Operation

Fuel Pump Assembly:

A fuel pump assembly is used, which includes a high-pressure fuel pump and a fuel level sensor. The fuel tank has an internal cavity (reservoir) in which the fuel level sensor and fuel pump rests. This design provides fuel pump operation during extreme vehicle maneuvers and steep vehicle attitudes with low fuel tank fill levels.

The fuel pump and the fuel level sensor are mounted as an assembly. The outlet of the fuel pump includes a valve that maintains pressure in the fuel system after the vehicle is shut down. This pressure retention helps prevent long cranking times during hot-starting conditions.

The fuel pump has an internal relief valve to provide over-pressure protection in the event that fuel system flow becomes restricted or stopped. The fuel system pressure is controlled by a fuel pressure regulator on the engine.

The inlet of the fuel pump must be protected from contaminants which could jam or damage the internal fuel pump components. This is accomplished with a nylon mesh filtering element on the fuel pump inlet. The nylon filter element allows fuel to flow while keeping dirt and other contaminants out.

Power to the fuel pump is supplied by the Powertrain Control Module (PCM), through a fuel pump relay.