Fuel Pump Relay

If a prolonged crank is required to start vehicle, fuel pump relay may be faulty. To verify, start engine. With engine running, disconnect oil pressure switch (fuel pump back-up circuit). If engine stalls, fuel pump relay is faulty. If vehicle continues to run, relay is okay. Check for other causes of prolonged crank.
To test fuel pump relay, disconnect fuel pump relay. Refer to COMPONENT LOCATIONS . Apply battery voltage and ground to fuel pump relay winding terminals (control and ground). See Fig 1-7.
Using an ohmmeter, check continuity between fuel pump relay control and ground terminals. Continuity should exist. If continuity does not exist, fuel pump relay is defective.
To by-pass fuel pump relay on vehicle (fuel pump not operating), turn ignition off. Disconnect fuel pump relay connector. Using a fused jumper wire, connect fuel pump test connector to positive side of battery. Fuel pump should run.
If fuel pump runs, check for faulty connections to relay or replace defective relay. To locate fuel pump test connector, refer to COMPONENT LOCATIONS .

Fig 1: Fuel Pump Relay Schematic (4.3L "S" & "T" Pickup & Utility With A/T)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Fuel Pump Relay Schematic (4.3L A/T "C" & "K" Series)

Courtesy of GENERAL MOTORS CORP.

Fig 3: Fuel Pump Relay Schematic (4.3L "G" & "P" Series)

Courtesy of GENERAL MOTORS CORP.

Fig 4: Fuel Pump Relay Schematic (4.3L "L" & "M" Series)

Courtesy of GENERAL MOTORS CORP.

Fig 5: Fuel Pump Relay Schematic (4.3L VIN W "S" & "T" Pickup & Utility)

Courtesy of GENERAL MOTORS CORP.

Fig 6: Fuel Pump Relay Schematic (4.3L VIN Z "S" & "T" M/T)

Courtesy of GENERAL MOTORS CORP.