How To Replace Fuel Injectors


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Is your car taking more time to accelerate than usual and the smell of fuel is present in the cabin of your vehicle? If the answer is affirmative, then the possible cause can be occurred due to the faulty fuel injector.

Now you may be wondering that you might need to spend a pretty amount of time and money replacing it, but that is not true. Don’t worry about that anymore as using the guideline that we will provide you’ll save serious money if you have the little necessary skills and basic knowledge about engines.

But first, you need to be sure if the problem is really in fuel injectors, and not in the ignition coils. A fuel injector is reasonable for allowing fuel to enter the engine which is controlled by the car’s computer. Various sensors provide feedback information to the computer which adjusts the pulse width of the injector pintle valve that provides a spray pattern to help atomize fuel in the combustion chamber.

When to replace fuel injectors

Some of you may wonder what is the necessity of replacing fuel injector and when it is the pick time to replace the fuel injectors.

If you observed the following signs, then you need to be mentally prepared to replace the faulty fuel injectors.

  • If the Engine Light is on
  • If your vehicle’s engine continuously misfires
  • The fuel efficiency of the car begins to decrees significantly
  • If you can find fuel leaks around where the fuel injectors are mounted
  • If you find the bad odor of gas coming from the vehicle

So, if it’s don’t fire correctly the vehicle won’t have good acceleration and might get bad gas mileage – time to change the fuel injectors.

How to check for leaking fuel injector: main methods of identifying faulty fuel injectors

Sometimes people become doubtful and think that diagnosing fuel injectors and identifying whether the fuel injector is faulty is not possible on behalf of him. But the reality is totally opposite of your assumption. In fact sometimes it can be easier than you think, whether on a TBI (throttle body injection) or an EFI (electronic fuel injection) system.

  1. Faulty Fuel Injector Emits Bad Odour – you may find a strong smell of fuel in the vehicle cabin. Due to the leakage of fuel caused by the faulty fuel injector is the core reason behind it. So the bad odor in the cabin can be considered as a sign of a faulty fuel injector.
  2. Listening for Bad Fuel Injectors – you can use a mechanic’s stethoscope. First of all, place the stethoscope on each injector and listen carefully. In the injectors which are in good condition, there be a very distinct ticking sound. In the injector that is not functioning properly, there will be no ticking sound. Then, move the stethoscope back and forth between injectors a few times to get a clear image of the sound that it was supposed to make when it was working.
  3. Using Noid Light – Before removing the fuel rail to change the injector, you can test the electrical signal to the injector. You can perform a simple test know as lamp test using a parking light socket and bulb and plugging it into the wiring harness. If the light blinked, you will be able to know whether the injector is getting power or not if not then it must be stuck or bad. You can also buy a light and you need to plug it into the harness. You can do this simple test by yourself.

How to test fuel injectors with a multimeter

To test the fuel injector firing coil you can use an ohm multimeter. If you still don’t have it you can read our review on automotive multimeters to pick one.

Firstly, try to disconnect the wire around the injector and place the probes across the two contacts of the injector. An intact coil will provide you a read around 15 ohms. Once you have located the injector which is giving trouble you will have to remove the fuel rail to replace it in order to replace the faulty fuel injector.

How to change fuel injectors

Choosing the right injector for your car is highly important; otherwise, it makes no sense in replacing it with the one that does not fit the engine requirements. Know your engine model and based on the engine, buy a new injector. Replacing process may seem difficult initially but after a while, you will find that it is one of the easiest work you have ever done and it will be helpful to save you serious money.

  1. The first step is to remove the old and damaged injecting element, using a socket wrench set and a replacement kit, which would help you to remove the element easily from its place. For this, you will need to disconnect the battery negative terminal first, and later, remove the fuel hoses from the fuel and the electrical connectors. Before removing the hoses, do not forget to remove the pressure inside the fuel system by removing the fuel pump fuse or relay, with an engine ON.
  2. After that disconnect the vacuum hose from the fuel pressure regulator. Now, disconnect the fuel rail using a socket wrench to remove the mounting bolts. This will cause the fuel rail to get detached from the engine.
    You may require a small push to remove these injecting fragments from the rail. Once they get removed, also remove the O-rings from them and do not use these rings again.
  3. Now you can install the new fuel injector to the fuel rail with a new O-ring, and connect the fuel rail back to the engine. Connect the fuel hoses and the battery cable to complete the installation process.
  4. After all, connect the vacuum hose to the pressure regulator, and also connect the fuel pump fuse or relay back to its place. Finally, start the engine. This will cause the pressure to get back to normal inside the system.

Bonus tips for maintaining fuel injector to make it last longer

Fuel injectors are very tiny and perform the meticulous job of properly supplying the engine with correct amounts of fuel. It’s not surprising that a small amount of debris in the system can cause noticeable problems. A professional fuel injection flush can do wonders for a dirty, clogged up the system as a high power chemical cleaning solution is passed through the fuel injectors in order to break up dirt, sludge, varnish, and carbon buildup. This potent solution will clear the way so that fuel may flow freely once again and be put to good use.

It’s also a good idea to stay away from cheap, discount gas as it does not contain the same cleaning agents and detergents that are in major brands of gasoline like Shell, Mobil, and Chevron. If you continue to use cheap, discount gas for an extended period of time, it’s likely that your fuel injection system will become dirty and clogged much quicker. You may even want to dump a small $4 bottle of fuel cleaner into your gas tank from time to time to help keep those fuel injector pathways free and clear.

QnA section

How long do fuel injectors last?

Depending on your type (quality) of gas and oil filter change frequency it will last from 50,000 miles to about 100,000 miles. On average we would recommend you to change them every 60,000-80,000 miles.

What is a fuel rail?

The fuel rail is the long, round metal bar that runs along the top of the injectors and is held onto the manifold with a few bolts. The main function of the fuel rail consists in the optimal distribution of the fuel (gasoline, methane, etc.) to the injectors in the high or low pressure supply systems of endothermic engines.

How long does it take to replace fuel injectors?

It shouldn’t take more than 2 hours or so if you are mechanically inclined.

Is it better to clean or replace fuel injectors?

If you started to ask this question, then it’s better to replace them 🙂

To sum it up

At the end of the day, we hope that from now you can replace your own fuel injector without any problems. Moreover, you will be able to keep your fuel injector fit for a long time by following the above-mentioned tips and tricks. Also, if you still have questions you can ask them in comments or in our Facebook group.

Dan Hoffman

Dan is a co-founder of Engineswork. He knows everything about internal combustion engines. Ask your questions in comments down below this article - he will be glad to help you anytime.

2 thoughts on “How To Replace Fuel Injectors

  1. graham kniese says:

    1uz v8 sureing at idol 1000 rpm rising 1500 can you give me some help to get to idol

    1. Dan Hoffman says:

      Hi, Graham. Take a look at this video https://youtu.be/UO-En1w4HFY

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