System Description

When ignition switch is turned on, the Engine Control Module (ECM) enables the fuel pump relay, which in turn powers the fuel pump. The fuel pump remains ON as long as the engine is cranking or running and the ECM receives ignition reference pulses. If there are no ignition reference pulses, the ECM shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position, or if the engine stops.

The fuel pump is an electric pump that is attached to the right fuel tank module assembly. The fuel pump also supplies fuel to the siphon jet pump, also attached to the right fuel tank module. The siphon jet pump draws fuel from the left side of the fuel tank to the right side of the fuel tank. The fuel pump is designed to provide fuel at a pressure above the pressure that is needed by the fuel injectors. Unused fuel is returned to the fuel tank by a separate fuel return pipe. A fuel pressure regulator, which is located on the fuel rail assembly, keeps the fuel available to the fuel injectors at a regulated pressure. The port on the fuel pressure regulator is an atmospheric vent. The fuel pressure regulator does not compensate for changes in intake manifold vacuum.