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 Flow Chart, Fuel Pump Relay

Courtesy of GENERAL MOTORS CORP.

Fig 2: Chart A-5 Schematic, Fuel Pump Relay

Courtesy of GENERAL MOTORS CORP.