How To Test The Fuel Injectors (1992-1994 3.0L Ford Ranger)

How To Find The Bad Fuel Injector

Testing the fuel injector resistances on your 3.0L Ford Ranger (Ford Aerostar) can seem quite the challenge. Especially because you'll need to remove the upper intake manifold Blenheim to test three of them.

Throughout the years I've been working on cars, I have developed a strategy that has helped me find the root cause of the cylinder misfire (whether it was caused by a fuel injector or not).

So in this section are a few of the suggestions that I think will help you to save time (and frustration) in trying to locate the defective or clogged fuel injector that's causing your Ford Ranger's engine to misfire:

1. Identify the dead cylinder first.
   • This means that you will have to do a manual under balance test to find the misfiring cylinder.
2. Verify that the dead cylinder is getting spark.
   • To get the most accurate test result, it's important that you use a dedicated spark tester for this test.
   • You also need to remove the spark plug and check that it is not damaged in any way shape or form.
   • Make sure that the spark plug boot is not damaged or covered in a carbon track. You can find out more about carbon tracks here: Carbon Tracks Are A Common Cause Of Ignition Misfires.
   • The idea here is to make sure that the ignition system is not behind misfire problem.
3. Once you have confirmed that the dead cylinder is getting spark then the next step is to make sure that it has good compression.
   • The following tutorial will help you to check and interpret your compression test results: How To Do And Interpret An Engine Compression Test (Ford 3.0L, 3.8L) (at: troubleshootmyvehicle.com.

So, the idea behind this strategy of tests is to eliminate all of the other possibilities that could cause a misfire before starting to test the fuel injectors (specially if dead cylinder;s fuel injector is located under the intake manifold plenum).

Also, to be able to obtain an accurate result, the very first step is to identify the dead cylinder before you do any testing.

The Intake Manifold Plenum Has To Be Removed

What complicates testing the fuel injectors that belong to cylinders 1, 2, and 3 is fact that you need to remove the upper intake manifold to get access to them.

Having done this job quite a few times myself, here is a list of suggestions that will help you avoid any complications or headaches:

1. Once you remove the plenum and the lower intake manifold ports are exposed, make sure that nothing (like a bolt or a washer or any other metal component) falls into them.
2. As you're removing bolts (or nuts), place them in a container that's located away from the engine compartment.
3. Once you have removed intake manifold plenum, place clean shop towels over the lower intake manifold ports.

If anything falls into any one of the 6 ports of the lower intake manifold, and you start the engine -you're gonna' be in a world of hurt. The only way to remove whatever fell into the engine is to remove the cylinder head (or heads). Also, the engine can suffer piston or cylinder head valve damage as the metal object bounces around the cylinder.

More 3.0L Ford Tutorials

You can find a complete list of 3.0L Ford tutorials in this index: Ford 3.0L Index Of Articles.

Here's a sample of the tutorials you'll find in the index:

• How To Test The TPS (1993-1994 3.0L Ford Ranger).
• Tune Up And Torque Specifications 1991-1994 3.0L Ford Ranger.
• 1992-1994 3.0L Ford Ranger Fuel Injector Wiring Diagram.
• 1992-1994 3.0L Ford Ranger Ignition Control Module Wiring Diagram.