Fuel Pump Operation

After the low pressure fuel is filtered by the fuel filter, it enters the high pressure fuel injection pump. When the fuel reaches the high pressure pump, a portion of the fuel flows to the lubrication valve allowing the fuel to lubricate the mechanical components of the high pressure injection fuel pump. Fuel that is not used for pump lubrication is directed to the fuel volume control valve. The fuel volume control valve regulates how much fuel enters the inlet one way check valve. For additional information, refer to ENGINE CONTROL COMPONENTS , Fuel Volume Control Valve. The outlet check valve ball remains closed while the fuel is drawn in due to suction. Fuel rail pressure is controlled by the fuel volume control valve.

During certain driving conditions the PCM cycles the fuel pump on and off for testing purposes and is considered normal operation.