Fuel Pump: Description and Operation

SYSTEM OPERATION
The fuel pump used in this system has a permanent magnet electric motor. The pump is part of the fuel pump module. Fuel is drawn in through a filter at the bottom of the module and pushed through the electric motor gearset to the pump outlet.

Check Valve Operation: The pump outlet contains a one-way check valve to prevent fuel flow back into the tank and to maintain fuel supply line pressure (engine warm) when pump is not operational. It is also used to keep the fuel supply line full of gasoline when pump is not operational. After the vehicle has cooled down, fuel pressure may drop to 0 psi (cold fluid contracts), but liquid gasoline will remain in fuel supply line between the check valve and fuel injectors. Fuel pressure that has dropped to 0 psi on a cooled down vehicle (engine off) is a normal condition. Refer to the Fuel Pressure Leak Down Test for more information.

Voltage to operate the electric pump is supplied through the fuel pump relay.