Fuel Pump: Description and Operation

Fuel Pump Cross Section:

The electric fuel pump located in the fuel tank consists of an armature, magnet, impeller, brush, check valve, relief valve, etc. The control relay and the ECM control its "ON/OFF" operation.

When power is supplied to the fuel pump, the motor in the pump runs and so does the impeller. This causes a pressure difference to occur between both sides of the impeller as there are many grooves around it. Then the fuel is drawn through the inlet port, and with its pressure increased it is discharged through the outlet port. The fuel pump also has a pressure relief valve to prevent excessive rise of the discharge pressure and a check valve to keep some pressure in the fuel feed line even when the pump is stopped.