How To Test a Ford Ranger Fuel Injector

How To Test a Ford Ranger Fuel Injector


When your Ranger fuel injector fails or becomes clogged, it’s going to cause serious issues for your Ford pickup truck. Outright failure of your Ford fuel injector will change the internal resistance of the device. This makes it simple to test the Ranger fuel injector through the use of a digital multimeter. Measuring the internal resistance of your truck’s fuel injector will let you know if the internal windings have gone out or not.

Similarly, the use of bad gas or a faulty fuel filter can also lead to your Ford Ranger fuel injector becoming clogged. This will also cause a similar issue with your truck, causing misfire and an inconsistent idle. Today I’ll be showing you how to test the Ranger fuel injector in a 1997 Ford truck. Our truck is equipped with a 2.3 liter 4 cylinder engine in it, although the testing procedure is similar for the V6.

If you suspect that your fuel injector is going bad, or your Ford Ranger check engine light is on, this guide can help. Of course if your Ranger check engine light is on, you’ll need a OBDII scan tool to properly retrieve your stored Diagnostic trouble code.

Test a Ford Ranger fuel injector 1

Using a OBDII scan tool to read your Ranger trouble code can help you. Problems with your Ranger fuel injector can result in several different codes cropping up. Here’s a look at the common Ranger misfire trouble codes that could be stored in your engine computer.

  • P0300: Random Cylinder Misfire – If you have this trouble code, scroll down to “Locate failed Ranger fuel injector” section for more information.
  • P0301: Cylinder #1 Misfire – To locate cylinder 1 you can look at the front of your engine and track cylinder 1 to the spark plug that’s closest to the front of your 4 cylinder engine.
  • P0302: Cylinder #2 Misfire
  • P0303: Cylinder #3 Misfire
  • P0304: Cylinder #4 Misfire

Testing your Ford Ranger fuel injector

Using your digital multimeter, turn the dial to read resistance or OHMS. For a 4 cylinder Ford Ranger like our test vehicle, you’ll need to unclip the top of the intake system. This will allow you to unplug each injector at a time.

It’s also good to have a pad and pen handy to record your findings. Once you have disconnected the Ranger fuel injector harnesses, you can begin testing. To do so you will need to probe PIN 1 and PIN 2 using the Ford Ranger fuel injector wiring diagram below.

Test a Ford Ranger fuel injector 2


Measuring the internal resistance of your Ford Ranger fuel injector will show you whether or not the injector has failed, or simply clogged. For this year range of Ford truck from 1994-1997, the resistance value should fall between 11 to 18 Ω. If you own a 1990-1993 Ford Ranger the resistance is between 15 to 18 Ω.

If your Ford Ranger fuel injector doesn’t respond within the specifications, it’s time to remove it and install a replacement. Shop our replacement fuel injectors to find the replacement part you need.

Locate failed Ranger fuel injector

If you have a random misfire code, or own a V6 Ford Ranger, this test can help you locate the problem injector. Because your OBDII engine computer doesn’t specifically know which cylinder has the misfire issue, you can load balance test your truck to find the problem.

To do this, you will need to simply start your engine and allow it to idle. Load balance tests are also known as a cylinder balance test. To begin all you need to do is unplug one injector at a time while your truck is idling.

This test will show you how to find the bad Ranger fuel injector in your truck. When you unplug and injector and the idle doesn’t get worse, that means the injector you unplugged is the problem one. Unplugging a healthy fuel injector should cause your idle to dip and your truck may threaten to shut off all together.

If your Ranger idle does get worse, that means that cylinder is good and the injector isn’t the cause of your Ranger misfire. There are also other causes or problems that can contribute to engine misfire in your Ford truck. Issues can range from ignition problems to lack of cylinder compression as well.

Checking your Ford Ranger fuel system

If all of your Ford Ranger fuel injector resistance values seem good, and the load balance test doesn’t reveal much you may need to test the fuel system. To do this you’ll need the right automotive noid light set to test the EFI system in your truck.


Using a noid light plugged into the wiring harness of your Ranger fuel injector will show you whether or not your EFI system is at fault. Have any questions about this guide to test your Ford Ranger fuel injector? Leave us a comment below and let us know!