Although the 3.3L V6 Buick and Oldsmobile vehicles don't come equipped with a Schrader valve on the fuel injector rail, testing the fuel pump still isn't that difficult.
In this tutorial, I'll explain how to test the fuel pump pressure with a fuel pressure test gauge. I'm also including how to do a starting fluid test which will help you find out if the engine is not starting due to a lack of fuel.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar La Bomba De Combustible (1989-1993 3.3L V6 Buick, Oldsmobile) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 3.3L V6 Buick Century: 1989, 1990, 1991, 1992, 1993.
- 3.3L V6 Buick Skylark: 1989, 1990, 1991, 1992, 1993.
- 3.3L V6 Oldsmobile Achieva: 1992, 1993.
- 3.3L V6 Oldsmobile Calais: 1989, 1990, 1991.
- 3.3L V6 Oldsmobile Cutlass Ciera: 1989, 1990, 1991, 1992, 1993.
Symptoms Of A Bad Fuel Pump
Fuel pump failures usually cause one of two types of 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 a quick disconnect adapter to test the fuel pressure on your 3.3L V6 Buick or Oldsmobile (since the fuel rail doesn't have a Schrader valve).
You'll also need a quick disconnect tool to disconnect the fuel line (to insert the adapter).
The following kits include the tools you need:
Using A Fuel Pump Pressure Tester To Test The Fuel Pump
To connect a fuel pressure test gauge to the fuel system, you'll need to use a 3/8" quick disconnect fuel pressure test adapter (see photo 2 of 3 above).
This adapter has to be installed between the fuel rail and the 3/8" fuel feed line (that comes from the fuel filter). The orange arrow in photo 1 of 3 above points to this fuel line.
To disconnect the fuel line, you'll need a quick disconnect fuel line tool (see photo 3 of 3 above).
NOTE: If you don't have a fuel pressure tester with the correct adapter or don't have the quick disconnect tool, take a look at this section: Where To Buy A Fuel Pressure Test Gauge.
The fuel pump pressure for the 1989-1993 3.3L 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.
OK, these are the test steps:
Place a shop towel around the fuel pressure line (where it connects to the fuel injector rail).
The shop towel's job is to absorb any fuel that may leak when doing step 2.
Disconnect the fuel pressure line from the fuel injector rail.
NOTE: You'll need to use a quick-disconnect tool to disconnect the fuel pressure line from the fuel injector rail.
Connect the test adapter between the fuel pressure line and the fuel injector rail.
Connect the fuel pressure gauge to the adapter.
When ready, ask your helper to cycle the key ON and OFF several times but don't crank the engine while you observe the fuel pressure tester's gauge.
Check your connections for fuel leaks.
Crank the engine and check the fuel pressure gauge.
Your 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 confirms that the no-start problem is caused by a lack of fuel.
This usually means that the fuel pump is bad and needs to be replaced.
CASE 2: The fuel pressure gauge registered the indicated fuel pressure specification. This fuel pressure gauge result lets you know that the fuel pump is working and delivering enough fuel to the fuel injectors. You can conclude the fuel pump is OK and not behind the no-start problem.
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.