Fuel Pump

An in-tank electric fuel pump delivers fuel to injectors through an in-line fuel filter. The pump is designed to supply fuel pressure in excess of vehicle requirements. The pressure relief valve in the fuel pump controls maximum fuel pump pressure.

A pressure regulator, mounted in fuel rail (port injection systems) or on throttle body unit (throttle body injection systems), keeps fuel available to injectors at a constant pressure. Excess fuel is returned to fuel tank through pressure regulator return line. For fuel pressure specifications, see FUEL SYSTEM in the appropriate article below:

• SPECIFICATIONS - 4-CYL
• SPECIFICATIONS - V6
• SPECIFICATIONS - V8

When the ignition switch is turned to the ON position, ECM will turn on the electric fuel pump by energizing the fuel pump relay. The ECM will continue to energize relay if the engine is running or cranking (ECM is receiving reference pulses from the ignition module). If no reference pulses exist, ECM de-energizes fuel pump relay within 2 seconds after ignition is turned on. For additional information, see FUEL PUMP RELAY.