How to Check the Fuel Pressure in a 1999 Pontiac Grand Am

by Leonardo R. Grabkowski

Engine misfiring, rough idling and reduced performance could be caused by low-fuel pressure. On the flip side, engine surging, frequently-faulty spark plugs and dark-tailpipe emissions could be caused by high-fuel pressure. The 1999 Pontiac Grand Am's fuel system is complicated; numerous factors can contribute to too-high or too-low fuel pressure. Checking the fuel pressure to make sure it's inline with the manufacturer's recommendations can help you diagnose the problem.

Step 1

Turn your air-conditioner switch off, and then turn the ignition off. Open the hood and support it with the prop.

Step 2

Inspect the rear part of the engine compartment near the intake manifold. Look for the fuel rail and the fuel-pressure test port. This port has a small Schrader cap on it. Twist the Schrader cap off to access the test port.

Step 3

Attach the fuel-pressure gauge's fitting to the test port. Turn the ignition to the "On" position (don't crank the engine) to activate your fuel pump. Ideally, someone does this for you while you observe the fuel-pressure gauge.

Step 4

Examine the fuel-pressure gauge. The reading should be between 41 and 47 psi. If the reading is too low, the likely culprit is a clogged-fuel filter. If the reading is too high, a number of problems could be the cause, including the fuel-pressure regulator.

Step 5

Turn the ignition back to "Off," and disconnect the fuel-pressure gauge. Replace the Schrader cap.

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