The fuel pump pressure test is not difficult to perform on the 1991-1994 Ford Ranger with a 3.0L V6 engine.
In this tutorial, I'll explain the fuel pressure test procedure. With your test result, you'll quickly determine if the fuel pump is good or bad.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar La Bomba De Combustible (1991-1994 3.0L V6 Ford Ranger) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 3.0L Ford Ranger: 1991, 1992, 1993, 1994.
- 3.0L Mazda B3000: 1994.
NOTE: The following tutorials will help you test the fuel pump on the 1995-2001 3.0L Ford Ranger:
- How To Test The Fuel Pump (1995-1997 3.0L V6 Ford Ranger)
- How To Test The Fuel Pump (1998-2001 3.0L V6 Ford Ranger).
Symptoms Of A Bad Fuel Pump
The job of the fuel pump is to deliver fuel to the engine so it can start and run.
As the fuel pump wears out and fails, it will cause one of two problems.
- An engine no-start problem.
- An engine performance problem.
A fuel pump failure doesn't always result in an engine no-start problem. In some cases, the fuel pump runs but does not produce enough pressure to keep the engine running at peak performance.
A faulty fuel pump that isn't producing enough fuel pressure will cause one or more of the problems listed below:
- 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 no-start problem or an engine performance problem, a fuel pressure test will help you determine if it is the source of the problem.
Where To Buy A Fuel Pressure Test Gauge
To check the fuel pump, the fuel pressure tester requires an adapter for the Ford Schrader valve. Without it, you cannot connect the tester to check fuel pressure.
The fuel pressure gauges in the list below are quality tools and all come with the Ford Schrader valve adapter.
Disclosure: As an Amazon Associate, I earn from qualifying purchases. Buying through these links helps support this site at no extra cost to you. Thanks for your support —it really means a lot!
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
To accurately test if your fuel pump is good or bad, you need to use a fuel pressure gauge.
If the fuel pump is functioning properly, its fuel pressure value will be within the specified fuel pressure specification.
If the fuel pump is defective, the fuel pressure recorded by the fuel pressure gauge will not be within 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).
NOTE: The Schrader valve is located on the fuel injector rail, next to the fuel pressure regulator and on the passenger side of the engine.
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 read 0 PSI. This confirms that the fuel pump is not supplying the fuel the engine needs to start.
This usually means that the fuel pump is bad 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 no-start 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.
Using Starting Fluid
Using starting fluid is another method to diagnose an engine no-start problem.
The starting fluid is sprayed into the throttle body and then the engine is cranked.
If the engine was not starting due to lack of fuel, it will now start and run for a few seconds.
While it's not the most accurate way to test a fuel pump, it can point your diagnostic efforts in the right direction.
I've used the starting fluid test a few times to begin my engine no-start diagnostic with good results.
IMPORTANT: The accuracy of the starting fluid test depends on all six spark plugs delivering sparks to their cylinders. If you have not checked the spark plug wires for spark (using a spark tester), do so before beginning the test. Otherwise, you may get a false positive result with this test.
These are the test steps:
- 1
Remove the intake air duct from the throttle body.
You don't have to completely remove it, since you'll have to reconnect it in one of the next steps. - 2
Open the throttle manually, and spray starting fluid down the bore.
- 3
Quickly reconnect the air duct to the throttle body (you don't have to tighten the hose clamp) when you have sprayed a good squirt of starting fluid.
Reconnecting the intake air duct is a very important safety precaution in case you get a back-fire thru' the intake manifold. - 4
Crank the engine once the intake air duct is back on the throttle body.
- 5
You'll get one of two results:
1.) The engine will start momentarily and after a few seconds will die.
2.) The engine will only crank but not start at all.
OK, let's analyze your test result:
CASE 1: The engine started and ran for a few seconds. This result confirms that the engine no-start problem is caused by a lack of fuel.
I suggest your next step is to test the fuel pump fuel pressure with a test gauge. For this test go to: Using A Fuel Pump Pressure Tester To Test The Fuel Pump.
CASE 2: The engine DID NOT start, not even briefly. This result generally tells you that a lack of fuel is NOT the reason the engine won't start.
Remember what I said about this test not being very accurate? Well, I suggest you do one more test and test the fuel pressure with a fuel pressure tester. For this test go to: Using A Fuel Pump Pressure Tester To Test The Fuel Pump.
More 3.0L V6 Ford Ranger Tutorials
You can find a complete list of 3.0L V6 Ford Ranger tutorials here:
Here's a sample of the tutorials you'll find in the index:
- How To Test The Engine Compression (1991-2008 3.0L Ford Ranger).
- How To Test The Blower Motor (1998-2000 3.0L Ford Ranger).
- How To Test The Blower Motor Switch (1998-2000 3.0L Ford Ranger).
- How To Test The MAF Sensor (1998-2001 3.0L V6 Ford Ranger).
If this info saved the day, buy me a beer!
