Fuel Lift Pump Electrical Circuit
DESCRIPTIONWhen the key is first turned ON without the engine running, the control module turns the fuel lift pump relay ON during glow plug cycle. This builds up fuel pressure quickly. If the engine is not started after the glow plug cycle, the control module shuts the fuel lift pump OFF and waits for engine rpm. As soon as the engine is cranked, the control module turns the relay ON and runs the fuel lift pump.
As a backup system to the fuel lift pump relay, the fuel lift pump is also turned ON by an oil pressure switch. When engine oil pressure reaches about 28 kPa (4 psi) through cranking, the oil pressure switch will close to complete the circuit to the fuel pump.
For the location of the fuel pump relay, refer to Engine Controls Component Locations. For diagnosis of the lift pump electrical circuit, refer to Diagnostic Tables / System Diagnostic Tables / Fuel Pump Relay Circuit Diagnosis. Testing and Inspection