Test Your Fuel Injectors – Guide

Auto fuel injectors provide the right air and fuel mix to the engine of your car. They are usually small and cylindrical even in large fuel intake systems. Car owners are advised to maintain these injectors and perform regular checks to ensure they are functioning properly.

Test Your Fuel Injectors - Our guide

They are exposed to various kinds of wear, but you can make sure they are effective by testing them regularly. Here is a quick guide by auto pros on how to test your fuel injectors and determine if they are working properly. The tests should ideally begin with your vehicle on a level ground with the parking brake set and the engine off.

The usual fire precautions are vital as there may be fuel during these tests. Also, remember to use protective eyewear and gloves for safety.

Check the engine idle

Start your car engine and leave it running for two minutes so as to stabilize the idle. Open the hood and disconnect one of the fuel injectors. See if the idle is still the same or worse. If the idle is worse, then the injector is dead. Use a long metal rod such as a screwdriver to touch the injector rod.

Place your ear to the other end of the rod to check for an audible clicking sound. Repeat this process with all the fuel injectors. A clunking sound is a good indicator that the injector is faulty.

Check your coil resistance

Set your ohmmeter multimeter to ohm settings, and disconnect the electrical connect from one injector. Attach the connecting leads of the multimeter or ohmmeter to the electrical prangs of the fuel injector.

Repeat this procedure for all the injectors noting the meter readings. If one injector has too low or high reading compared to the rest, then it is defective.

Flow meter

You will need to use a flow meter to check the rate of fuel flow to your engine. Clogged injectors have a lower flow rate.

If you notice lower flow rate, be sure to clean the injected so as to improve engine performance as well as the fuel flow rate.


Check the spray pattern

Faultless fuel injectors have a regular spray pattern. An irregular pattern is a clear indication that the injectors are dirty and less fuel is entering the engine.

You can check the spray pattern by simply opening the hood and placing a bright LED light just above the spray pattern.


Check the injector tips

Rub your finger over the tip of each injector to determine if it leaking or clogged with carbon or dirt. If the injector is clogged, it is recommendable to use manual fuel injector machines to clean the injector.

The machines will not only clean the injectors but also unclog the injectors to make them work better.



In addition to the above tests, it is good to check other parts such as the fuel filter. A defective fuel filter will impact on the efficiency of your fuel injectors.

Finally, consider preventative maintenance measures like ensuring that you check and clean the injectors at least once a year or for every 25,000 miles covered.

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