Diagnostic Aids

Inoperative fuel pump relay can cause long engine cranking before starting. The long crank period is caused by time needed for engine to build up oil pressure and energize fuel pump through back-up circuit.

Fig 1: Chart A-5 Schematic - Checking Fuel Pump Relay

Courtesy of GENERAL MOTORS CORP.

Fig 2: Chart A-5 Flow Chart - Checking Fuel Pump Relay

Courtesy of GENERAL MOTORS CORP.