Fuel Pump: Description and Operation

Fuel Tank And Components (2WD):

The electric fuel pump is installed in the fuel tank. It is submerged in the fuel, which proves an excellent suppressor of pump operational noise and improves vapor lock resistance. This pump is called "wet type" because the inside is filled with fuel. The pump itself is composed of a motor-driven impeller, casing and cover. A relief valve (to protect against over pressure) and a check valve (to retain pressure in the system) are incorporated into the pump housing. When the impeller is rotated by the DC motor, a pressure difference is produced across the impeller because of the grooves in the circumference of the impeller.

High Pressure Elecric Fuel Pump:

The operation of the fuel pump is controlled by the ECU through the control relay. Power is supplied to the fuel pump by the control relay through separate circuits for cranking and run modes. In the event of engine stall or other abnormal conditions, the ECU interrupts the fuel pump power circuit. For a more detailed description of the control relay, refer to COMPUTERIZED ENGINE CONTROLS.
NOTE: Failure of the control relay may interrupt power supply to the fuel pump, injectors and/or the ECU, resulting in start failure.