In this tutorial, I'll explain how to test the fuel pump with a fuel pressure test gauge.
I've also included the instructions on how to perform a starting fluid test (which will help you confirm if an engine no-start problem is due to a lack of fuel).
All of the tests are explained in detail so that you find out if the fuel pump is bad or not.
Contents of this tutorial:
APPLIES TO: This tutorial applies to the following vehicles:
- 3.1L V6 Buick Century: 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005.
- 3.1L V6 Buick Regal: 1994, 1995, 1996.
- 3.1L V6 Buick Skylark: 1994, 1995, 1996.
- 3.1L V6 Oldsmobile Achieva: 1994, 1995, 1996, 1997, 1998.
- 3.1L V6 Oldsmobile Cutlass: 1997, 1998, 1999.
- 3.1L V6 Oldsmobile Cutlass Ciera: 1994, 1995, 1996.
- 3.1L V6 Oldsmobile Cutlass Supreme: 1993, 1994, 1995, 1996, 1997.
Symptoms Of A Bad Fuel Pump
For the most part, when a fuel pump fails, it'll cause one of two problems:
- Either the engine will not start
- - or -
- The engine starts and runs, but runs very badly.
If the fuel pump still functions, but doesn't send the correct amount of fuel, you'll see one or more of the following symptoms:
- Engine takes longer than usual to start (extended cranking).
- Engine idle is very rough.
- Engine backfires thru' the intake manifold under load.
- Engine starts, then dies.
Both can be diagnosed with a simple fuel pump pressure test.
Where To Buy A Fuel Pressure Test Gauge
You'll need a fuel pressure test gauge and the correct adapter to test the fuel pump pressure on your vehicle.
The following kits include the tools you need:
Using A Fuel Pump Pressure Tester To Test The Fuel Pump
The fuel injector rail, on your vehicle's engine comes equipped with a Schrader valve.
It's to this Schrader valve that we're going to connect the fuel pressure tester gauge via an adapter.
The Schrader valve is located on the side of the engine facing the serpentine drive belt, beside the power steering pump reservoir.
The orange arrow in the photo above points to the Schrader valve.
NOTE: If you don't have a fuel pressure tester with the correct adapter, take a look at this section: Where To Buy A Fuel Pressure Test Gauge.
The fuel pump pressure for the 1993-1999 3.1L V6 Buick and Oldsmobile vehicles is:
- 40-47 PSI Key On With Engine Off.
- With Key On Engine Running, fuel pressure should drop 3 to 10 PSI.
The fuel pump pressure for the 2000 3.1L V6 Buick Century is:
- 48-55 PSI Key On With Engine Off.
- With Key On Engine Running, fuel pressure should drop 3 to 10 PSI.
The fuel pump pressure for the 2001-2005 3.1L V6 Buick Century is:
- 52-59 PSI Key On With Engine Off.
- With Key On Engine Running, fuel pressure should drop 3 to 10 PSI.
OK, these are the test steps:
- 1
Place a shop towel under the Schrader valve. The shop towel's job is to absorb any fuel that may leak when doing step 2.
- 2
Connect the fuel pressure gauge to the Schrader valve.
Most fuel pressure gauges can be connected to the Schrader valve without an adapter. If yours isn't one of them, connect the correct adapter to the Schrader valve and then connect the gauge to it. - 3
When ready, ask your helper to cycle the key on and off but don't crank the engine while checking for fuel leaks.
If no fuel leaks, go to next step.
If fuel is leaking, resolve the leak before continuing to the next step . - 4
Crank the engine and observe the fuel pressure gauge.
- 5
The fuel pressure gauge should register the specified fuel pressure.
Let's take a look at your fuel pressure test results:
CASE 1: The fuel pressure test gauge registered 0 PSI. This test result confirms that the engine is not starting due to a lack of fuel.
You can conclude that the fuel pump is not functioning and is the cause of the engine's no-start problem.
CASE 2: The fuel pressure gauge registered the indicated fuel pressure specification. This is the correct and expected test result and it confirms that the fuel pump is OK.
CASE 3: The fuel pressure gauge registered a fuel pressure way below the specification. This test result lets you know that the fuel pump is failing. Replace the fuel pump.
