Fuel Pump Circuit Wiring Diagram (1992-1993 3.3L V6 Buick Skylark)

APPLIES TO: This fuel pump circuit wiring diagram applies to the following vehicles:

• 3.3L V6 Buick Skylark: 1992, 1993.

Fuel Pump Basic Operating Theory

When you first turn the ignition key to the ON position (without cranking the engine), the PCM turns the fuel pump relay ON for about 2 seconds. This short prime cycle allows the fuel pump to build fuel pressure before the engine is started.

If the engine isn't cranked during those 2 seconds, the PCM switches the fuel pump relay back OFF. Once you begin cranking the engine and the PCM starts receiving crankshaft position sensor signals, it energizes the relay again so the fuel pump continues to run.

This fuel pump circuit also has a built-in backup. The oil pressure switch is normally open, but it closes when engine oil pressure reaches approximately 4 PSI (28 kPa). If the fuel pump relay fails, the closed oil pressure switch can still provide power to the fuel pump after the engine develops enough oil pressure.

When diagnosing a fuel pump or fuel pump relay problem, keep the following points in mind:

• A failed fuel pump relay can cause a longer-than-normal cranking time before the engine starts, especially on a cold engine. This is because the fuel pump won't receive power until the oil pressure switch closes.
• If the fuel pump stops working completely, the engine will crank normally but it won't start.
• A weak fuel pump may still run, but if it can't produce the required fuel pressure, you may experience hard starting, hesitation during acceleration, lack of power, or engine misfires.

FUEL PUMP PRESSURE TEST: The following tutorial explains how to test the fuel pump with a fuel pressure test gauge:

• How To Test The Fuel Pump (1989-1993 3.3L V6 Buick, Oldsmobile).

ENGINE NO-START DIAGNOSTIC TESTS: Troubleshooting an engine no-start problem, the following tutorial explains the basics behind finding out what's causing the issue:

• How To Diagnose A No-Start Problem (3.3L V6 Buick, Oldsmobile).

1989-1991 FUEL PUMP CIRCUIT WIRING DIAGRAM:

• Fuel Pump Circuit Wiring Diagram (1989-1991 3.3L V6 Buick Skylark, Olds Calais).

More 3.3L V6 Buick Century Tutorials

You can find a complete list of 3.3L V6 Buick Century tutorials and wiring diagrams in this index:

• GM 3.3L Index of Articles.

Here's a sample of the tutorials you'll find in the index:

• How To Test The Throttle Position Sensor (1989-1993 3.3L V6 Buick, Oldsmobile).
• How To Test The MAF Sensor (1989-1993 3.3L V6 Buick, Oldsmobile).
• How To Test Engine Compression (3.3L V6 Buick, Oldsmobile).
• How To Test A Blown Head Gasket (3.3L V6 Buick, Oldsmobile).