How to Test Fuel Injectors: Essential Tips Car Owners Can Do Right Now

Do you have to press your gas pedal harder each time to get your car moving? Then your car’s fuel system might be in trouble. Your car may start showing a lot of other symptoms when the fuel is not properly delivered to the engine. A faulty fuel injector is one of the most obvious culprits of a malfunctioning fuel injection system.


Fuel injectors are basically solenoids that help control the amount of fuel delivered to actuate the pistons during combustion. A bad fuel injector can mess up with the operations of the engine.

If you want to do the test on your own, then you are on the right page! Here, I will show you how to test fuel injectors to help you get your engine back to its optimal performance.

Symptoms of a Bad Fuel Injector

Before you do any tests with the fuel injectors, you may want to know first the list of symptoms that your car might be showing off that will point to a failing fuel injector. I have summarized below the symptoms to help you determine a clogged or failed fuel injector:

  • Engine misfires
  • Decrease in power and acceleration
  • Poor fuel efficiency
  • Fuel odor due to leaks
  • Check engine light is on

Take note that most of the symptoms listed here may also indicate a bad spark plug. You can check what a bad spark plug looks like as well to see if this has also contributed to the engine issues of your car.

Why You Need to Test Your Fuel Injectors

Replacements of fuel injectors can be costly. However, you don’t want to do expensive replacements if it was not really needed in the first place. With the right diagnosis you can set a plan to solve your engine issues.

If you are not convinced about testing your fuel injectors now, then you better read my list of motivations below:

  • To help you troubleshoot the cause of your engine problems and take the right solutions.
  • To know which injectors are faulty, and know whether you need to just clean them or do a permanent replacement.
  • To help you get your engine’s optimal performance back.
  • To prevent safety hazards due to a faulty fuel injector, such as gas leaks.
  • To optimize the fuel delivery system, such as increasing fuel efficiency.
  • To prevent other engine issues from troubling you, such as difficulty in starting the engine and poor power and acceleration.

What Are the Steps to Check Faulty Fuel Injectors?

There are many options available to test a clogged or damaged fuel injector. But first, you need to know the right materials to use to get the test done.

Materials Needed:

1. Gloves

Gloves are accessories you will need as covering for your hand for protection against dirt and smudges you can get while testing the car engine.

2. Protective Eyewear

An eyewear is essential to protect your eyes from any nearby irritants or fluids while you check the parts and components of your vehicle.

3. Test Light


A test light is a convenient tool you can use to check the electrical power and grounding of your auto components.

4. Multimeter

A multimeter is an instrument utilized to measure electrical parameters like current, voltage, and resistance which can range on several values.

5. Fuel Pressure Gauge


In this post, you will need a fuel pressure gauge to help you determine if your fuel system produces pressure within the normal range.

6. Mechanic Stethoscope


A mechanic stethoscope is used to listen to the audible sounds your engine parts is producing to troubleshoot any issues faster.

Step by Step Instruction

Now you have all the materials needed, let’s get started!

Step 1: Prepare Your Car for the Testing

Step 2: Test for a Dead Fuel Injector Using a Multimeter

Step 3: Listen to the Fuel Injectors While the Engine Is Running

Step 4: Determine If the Fuel Pressure Is Within Range

Step 5: Check If the Fuel Injectors Have Constant Power

Step 6: Check the Fuel Injector Trigger Signal

All Done!

Faulty fuel injectors can totally mess up with your auto’s engine performance. But fear not! With the right methods, you can easily diagnose fuel injectors that are failing and be able to take the appropriate steps to correct the issues.

Have you enjoyed reading this primer? If you have found this article valuable, please do share this with your friends who share similar issues with their cars!

If you have something to share about testing fuel injectors, please don’t hesitate to include them in the comments section below!

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