Fuel Pump: Description and Operation

The Main Fuel Pump is mounted to the fuel gauge sending unit and is positioned inside the fuel tank. The Fuel Pump supplies a high rate of fuel to the fuel injection system. Operation of the pump is controlled by the fuel pump relay. The relay energizes the Fuel Pump briefly (approx. 1.5 sec.) when the ignition switch is turned "ON", as well as energizing the pump during cranking (starting). The fuel pump relay will keep the Fuel Pump energized as long as the engine is running. The Digifant fuel injection control unit uses an engine speed signal from the ignition system as an input for fuel pump control and will stop the Fuel Pump if the engine is not running. In order to maintain the pressure in the fuel system under all possible operating conditions, the pump supplies substantially more fuel than the engine needs at maximum engine loads.