How To Test a Mazda Protege Fuel Injector

How To Test a Mazda Protege Fuel Injector


There are four individual Protege fuel injector that fit into your Mazda fuel rail. Failure of this fuel injector can lead to problems with your Protege starting, or even cause engine misfire issues in your 1.8 or 1.6 liter engine. This pintle style fuel injector can also become clogged over time, leading to misfire or your Mazda running on three cylinders.

When this occurs you’ll need to test each injector to find out which one is the culprit. Today I’ll be showing you how to test a Protege Fuel Injector in a 2000 Mazda. This vehicle is equipped with the 1.8 liter engine in it, and the transverse layout makes testing your injectors easy.

In order to correctly track down the failed injector, you’ll need to use a digital multimeter. This How To guide will not only show you how to find the bad Protege fuel injector, but will also tell you if it’s clogged or simply dead. You’ll be using the multimeter to test the internal windings of the fuel injector. To do this you will need to turn the dial of your multimeter to read resistance or OHMS Ω.

testing mazda protege fuel injector 1

The four fuel injectors in your Mazda are located in the fuel rail. This is located on top of your engine and mounted in front of your intake manifold. To begin our Protege fuel injector testing guide, you will need to unplug your injector connectors.

Open your hood and locate your fuel rail, and then proceed to unplug all of your fuel injectors. It’s also a good idea to write down your findings on a notepad so that you can compare and find which Protege fuel injector is faulty in your engine.

Testing your Protege fuel injector resistance

Once you have the fuel injectors unplugged, you will be gently probing the two pins of the Protege fuel injector. Once you have a reading you will record it and move onto the next fuel injector.

testing mazda protege fuel injector 2The resistance of a good Protege fuel injector is between 12 and 16 OHMS Ω. Once you have tested one injector, move onto the next and record your findings at each step.

If you find one of your injectors falls outside of this range, it’s a sign that your injector has failed.

In the event that your fuel injectors test out, but your engine misfire is still obvious, this could be from a clogged injector. Over time the deposits in your fuel can clog the performance of your injector until it doesn’t work properly.

If you find that all your injectors test out with the proper resistance range, you will need to load balance your engine to find out which one is bad. To do this simply start your engine, and unplug one injector at a time. You are looking for the injector that doesn’t affect the engine idle as badly as a working fuel injector does.

Properly working fuel injectors will cause your engine to stumble further and nearly die. If you find that unplugging one Protege fuel injector doesn’t cause this to happen, it could be a clear sign that’s the injector that has clogged.

Remove your fuel injector and carefully remove your failed Protege fuel injector. Install a replacement with a new fuel injector o-ring and reinstall your fuel rail. Inspect the engine for any fuel leaks and test it thoroughly before driving the Protege again.

Have any questions about this Protege fuel injector testing guide? Leave us a comment below and let us know!