Download Circuit Description When you turn ON the ignition switch, the Vehicle Control Module (VCM) turns ON the in-tank fuel pump. The pump remains ON as long as the engine is cranking or running and the VCM is receiving reference pulses. If there are no reference pulses, the VCM shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position or if the engine stops. The VCM will also turn ON the fuel pump for 2 seconds when the ignition is turned to the OFF position. An electric fuel pump pumps the fuel through an in-line filter to the Central SFI unit. The pump is attached to the fuel level meter assembly inside of the fuel tank. The pump is designed to provide fuel pressure above what is needed by the fuel injectors. The pressure regulator keeps the fuel available to the injectors at a regulated pressure. Unused fuel is returned to the fuel tank by the fuel return pipe. Diagnostic Aids Tools Required • J 34730-1A Fuel Pressure Gage in J 34730-E or • J 34730-1A Fuel Pressure Gage with J 34730-250 Fuel Pressure Adapter Kit. Test Description The numbers below refer to the step numbers on the diagnostic table.