Fuel Pump: Description and Operation

Fuel Pump/Fuel Level Sending Unit Assembly:

The fuel pump is part of the fuel pump/level sending unit assembly, located in the fuel tank. The pump is a high pressure positive displacement, electric pump. Power for the fuel pump is provided by the fuel pump relay during cranking. when the engine is running, a switch in the oil pressure sensor provides power, as long as the ignition is "ON" and there is sufficient oil pressure.

The pressure relief valve in the pump will control maximum fuel pump pressure to 60-90 psi. The fuel pump delivers more fuel than the engine can consume even at wide open throttle/full load. Excess fuel flows through the pressure regulator and back to the tank via the return line. The constant flow of fuel means that the fuel system is always supplied with cool fuel, thereby preventing the formation of fuel vapor bubbles.