You may think fuel pump testing is difficult, but it isn't. Testing the fuel pump is not only a simple task, it also doesn't require expensive tools.
In this tutorial, I'll explain the fuel pump pressure test so you can find out if a fuel pump failure is causing an engine no-start problem or an engine performance problem.
Contents of this tutorial:
APPLIES TO: This tutorial applies to the following vehicles:
- 3.0L Ford Ranger: 1995, 1996, 1997.
- 3.0L Mazda B3000: 1995, 1996, 1997.
NOTE: The following tutorials will help you test the fuel pump on the 1991-1994 and 1998-2001 3.0L Ford Ranger:
- How To Test The Fuel Pump (1991-1994 3.0L V6 Ford Ranger).
- How To Test The Fuel Pump (1998-2001 3.0L V6 Ford Ranger).
Symptoms Of A Bad Fuel Pump
A bad fuel pump usually causes one of two problems:
- An engine no-start problem.
- An engine performance problem.
Yes, a fuel pump can fail and the engine can still start and run. Of course, the engine won't run optimally as the failed fuel pump will cause engine performance problems.
In these cases, the fuel pump will deliver just enough fuel for the engine, but once the engine is under load, one or more of the following problems will occur:
- 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.
- Lack of power when accelerating the engine under load.
- The check engine light illuminated by lean air/fuel mixture diagnostic trouble codes.
Whether the fuel pump is causing an engine starting problem or an engine performance problem, a fuel pump pressure test will help you determine the source of the problem.
Where To Buy A Fuel Pressure Test Gauge
The following fuel pressure tester kits include the Ford Schrader valve adapter you need to test the fuel pressure on your 1995, 1996, 1997 3.0L Ford Ranger and Mazda B3000.
Fuel Pump Pressure Specification
| Ford | ||
|---|---|---|
| Year/Engine/Model | KOEO | KOER |
| 1995-1997 3.0L Ranger | 35-45 PSI | 30-45 PSI |
| Mazda | ||
|---|---|---|
| Year/Engine/Model | KOEO | KOER |
| 1995-1997 3.0L B2300 | 35-45 PSI | 30-45 PSI |
KOEO = Key On Engine Off.
KOER = Key On Engine Running.
Using A Fuel Pump Pressure Tester To Test The Fuel Pump
The fuel rail of the 3.0L V6 engine on your Ford Ranger is equipped with a Schrader valve.
We'll connect a fuel pressure gauge to the Schrader valve to check the fuel pump pressure with the engine cranking or running.
If the fuel pump is faulty, you'll see 0 PSI or a pressure below the listed fuel pressure specification.
If the fuel pump is working properly, your fuel pressure gauge should show a fuel pressure within the specified specification.
IMPORTANT: If the engine does not start, check the fuel pump inertia switch and reset it if necessary. A fuel pump inertia switch activated by a vehicle impact (or even just hitting the curb) will cut power to the fuel pump and cause an engine no-start problem. You can find out more about it and its location here: Fuel Pump Inertia Switch Commonly Asked Questions (1991-2008 3.0L Ford Ranger).
These are the test steps:
- 1
Remove the plastic dust cap from the Schrader valve.
- 2
Place a shop towel around the Schrader valve.
The shop towel's job is to absorb any fuel that may leak when doing step 2. - 3
Connect the fuel pressure test gauge to the Schrader valve.
- 4
When ready, ask your helper to cycle the key ON and OFF but don't crank the engine while you observe the fuel pressure tester's gauge.
Check your connections for fuel leaks. Resolve any fuel leaks before continuing to the next step. - 5
Crank the engine and check the fuel pressure gauge.
- 6
Your fuel pressure gauge should register the specified fuel pressure.
Let's interpret your test result:
CASE 1: The fuel pressure gauge shows 0 PSI. This confirms that the engine starting problem is caused by lack of fuel.
This usually means that the fuel pump is defective and needs to be replaced.
CASE 2: The fuel pressure gauge registered the specified fuel pressure specification. This test result lets you know that the fuel pump is working properly.
You can conclude that the fuel pump is fine and is not responsible for the engine starting problem.
CASE 3: The fuel pressure gauge has registered a fuel pressure well below specification. This test result indicates that the fuel pump is defective.
