If your Ford Ranger's fuel pump fails, the engine will not start or will start but run with performance problems.
Fortunately, testing the fuel pump isn't difficult and in this tutorial, I'll explain how to check fuel pressure with a fuel pressure gauge.
Your test results will help you 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 (1990-1994 2.3L Ford Ranger) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 2.3L Ford Ranger: 1990, 1991, 1992, 1993, 1994.
- 2.3L Ford B2300: 1994.
Wiring Diagrams: The following fuel system wiring diagrams are available:
- Fuel Pump Circuit Wiring Diagram (1990 2.3L Ford Ranger).
- Fuel Pump Circuit Wiring Diagram (1991-1992 2.3L Ford Ranger).
- Fuel Pump Circuit Wiring Diagram (1993 2.3L Ford Ranger).
- Fuel Pump Circuit Wiring Diagram (1994 2.3L Ford Ranger).
NOTE: The following tutorial will help you test the fuel pressure on the 1995-1997 2.3L Ford Ranger (Mazda B2300):
Symptoms Of A Bad Fuel Pump
Over the years that I've worked as an automotive technician, I've found that a fuel pump failure usually causes one of two problems:
- An engine no-start problem.
- An engine performance problem.
When the fuel pump failure does not cause an engine no-start problem, your Ford Ranger will experience one or more of the following engine performance problems:
- 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 or an engine performance issue, a simple fuel pump pressure test will help you diagnose the problem.
Where To Buy A Fuel Pressure Test Gauge
You'll need a fuel pressure tester with the Ford Schrader valve adapter to test the fuel pressure on your 1990-1994 2.3L Ford Ranger (Mazda B2300). Here are my recommendations:
Fuel Pump Pressure Specification
| Ford | ||
|---|---|---|
| Year/Engine/Model | KOEO | KOER |
| 1990-1994 2.3L Ranger | 35-45 PSI | 30-45 PSI |
| Mazda | ||
|---|---|---|
| Year/Engine/Model | KOEO | KOER |
| 1994 2.3L 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
What makes testing the fuel pump on the 2.3L Ford Ranger so easy is that there's a Schrader valve on the fuel injector rail.
We can connect a fuel pressure gauge to this Schrader valve and test the fuel pump pressure.
If the fuel pump is working properly, you should see the specified fuel pressure specifications in this section: Fuel Pump Pressure Specification.
If the fuel pump is bad, your fuel pressure gauge will report a fuel pressure under the fuel pressure specification.
NOTE: The Schrader valve is located on the rear of the fuel injector rail (near the engine firewall).
IMPORTANT: If the engine does not start, check the fuel pump inertia switch and reset it if necessary. A fuel pump inertia switch which has been 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 (1989-1997 2.3L Ford Ranger).
Let's get started:
- 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 the next step. - 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 behind the engine no-start problem.
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 test result lets you know that the fuel pump is working properly.
You can conclude that the fuel pump is fine and is not behind the engine no-start or engine performance problem.
CASE 3: The fuel pressure gauge has registered a fuel pressure well below the indicated specification. This test result indicates that the fuel pump is defective and needs replacement.
