Learning, Multimeter,

How to Test Fuel Injectors with a Multimeter

In my article below, ill teach you how to test a fuel injector with a multimeter.

Fuel injectors are vital to controlling the air-fuel ratio. A bad fuel injector can cause issues such as cylinder misfires, poor engine performance, harmful emissions, and bad fuel economy because of the impurities in the fuel. It is crucial to test fuel injectors regularly.

Quick steps to test fuel injectors with a multimeter:

  • Find the fuel injector
  • Lift the cover that protects the two prongs of the fuel injector
  • Set the multimeter to resistance mode
  • Place the two leads of the multimeter on the two prongs
  • Check the resistance with vehicles designed resistance value in manual

I’ll go into more detail below.

3 Steps To Testing Fuel Injectors With a Digital Multimeter

If you think for a moment testing a fuel injector is a difficult task, you are dead wrong.

With three simple steps, you can accurately test the fuel injectors. I will explain those three steps extensively in this section. So, let’s get started.

Step 1 – Identifying the Fuel Injector

First, you must locate the fuel injector.

Most people face difficulties when identifying the fuel injector. Honestly, finding the fuel injector is very easy. Open the hood. Then get the vehicle’s manual. Usually, a vehicle has similar numbers of fuel injectors to cylinders. That means if your vehicle has four fuel injectors, it has four cylinders.

Fuel injectors locate within the intake manifold. Confirm this from the vehicle’s manual.

mechanic getting the fuel Injector
Video | ChrisFix

These injectors connect to the fuel rail. So, lift off the fuel rail from the engine. Now you can see the fuel injectors on the fuel rail.

How to Remove Fuel Injectors from Your Vehicle

If you are planning to test injectors, first, you should learn how to remove them from your vehicle. Even though checking fuel injectors without removing them from the engine is possible, it is easy to separate the fuel rail. So, here is how you can do that.

1: First, make sure the vehicle is cold. Using a hot vehicle can cause fire from fuel leaks. Then unplug all the fuel injector connectors. (1)

mechanic in blue gloves unplugging the fuel injector connectors
Video | Scotty Kilmer

2: Loosen the bolts connecting the fuel rail and the fuel line. If there are hidden bolts, don’t forget to loosen them too.

mechanic with blue glooves loosen the bolts that connect the fuel rail
Video | Scotty Kilmer

3: Finally, lift off the fuel rail.

mechanic with blue gloves lifting off the fuel rail
Video | Scotty Kilmer

Step 2 – Setting Up Your Digital Multimeter

For the injector test, set up the multimeter for the ohm test. Most of the multimeters have the Ω symbol on the selector switch area. So, turn the switch to the Ω symbol.

Then insert the black lead into the COM port. And insert the red lead into the port that displays the Ω symbol. Now your multimeter is ready for the ohm test, aka resistance mode.

Step 3 – Compare the Resistance Values

Now remove all the covers that protect the two prongs of each fuel injector.

mechanic removing the covers that protect the two prongs of each fuel injector
Video | ChrisFix

Place a red lead on one prong and the black lead on the other prong. Check the multimeter and note down the ohm value. Apply the same process to the other fuel injectors.

red lead on one prong and the black lead on the other prong
Video | ChrisFix

Then check your vehicle’s manual for designed resistance value. If you cannot find it in the manual, do a quick search on the internet or contact the manufacturer. Now compare the design value and the test value. If the two values are the same, the fuel injector works properly. If the values show a noticeable difference, you are dealing with a bad fuel injector. (2)

mechanic using multimeter to test fuel injector
Video | ChrisFix

Keep in mind: If the design value is 16.5 ohms, the test value needs to be 16-17 ohms.

Importance of the Fuel Injectors

Before starting the testing process, we must understand why we are doing this injector test. Here is a brief explanation of fuel injectors and their importance.

Fuel injectors primarily act as a device that supplies pressurized fuel to the engine. After some time, these fuel injectors might get damaged or stop working forever. The main reason for this is the impurities in the fuel. Additionally, mechanical and electrical problems might be the reason for a bad fuel injector.

Either way, a faulty fuel injector can affect your vehicle in a very negative way. A damaged fuel injector can affect the overall performance of the engine and your vehicle. Therefore, keeping your fuel injectors in top-notch condition is crucial.

Take a look at some of our related articles below.

(1) fuel – https://www.sciencedirect.com/journal/fuel
(2) internet – https://www.britannica.com/technology/Internet

Video References

Scotty Kilmer


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About Sam Orlovsky

AvatarCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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