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How to Clean Fuel Injectors

One of the most important components of the fuel system in modern cars is the fuel injector. In the early days of engine technology, the fuel was delivered using a mechanical carburetor.

How to Clean Fuel Injectors

It worked well for many years but with the advent of the on-board computer, new fuel delivery systems were developed. The first systems focused on replacing the carburetor fuel bowl and mixing chamber with fuel injection.

The most recent systems (in use today) place the fuel injector right at the cylinder head, near the sparkplug. This is often called direct fuel injection, and these are the fuel injectors that we will focus on in this article.

What are the Fuel Injectors?

Fuel injectors are electronically controlled devices designed to spray a small amount of fuel directly into the combustion chamber of each cylinder.

Since they spray such small amounts of fuel, they are very susceptible to getting clogged by particles or carbon build-up. In most cases, the detergent in the fuel and the fuel filter will keep the fuel injector clean but not always.

If the fuel injector spray pattern is impacted, the on-board computer will detect this and store a code. Most of the time, this will result in the check engine light coming on. If the problem is not addressed in a timely manner, the car’s performance may be impacted. In extreme cases, the car may stall and not restart.

What are the Symptoms of Clogged Fuel Injectors?

Usually, the build-up of deposits and potential clogging of the fuel injectors happens over time. If your car is older and has high mileage, you may have already experienced some performance issues. Here are a few symptoms that would warn you that your fuel injectors need to be cleaned:

  • The check engine light is illuminated.
  • The car is misfiring.
  • The car has poor performance.
  • Fuel consumption has increased.
  • The car has a rough idle.
  • The car is sometimes hard to start.

Is Fuel Injector Cleaning Necessary?

Under normal circumstances, modern cars are designed to keep the fuel injectors operating optimally.

However, if your car is older and has high mileage, it might be a good idea to consider cleaning the fuel injectors.

Fuel injector cleaning kits are very affordable and easy to use if you have intermediate mechanical skills. This is really a good example of the old saying, an ounce of prevention is worth a pound of cure.

Can I Clean My Fuel Injectors?

This project will require an intermediate level of mechanical skill. You will be working with fuel and electrical components, so it is not for the entry-level mechanic.

If you are not confident that you can tackle this project, it might be best to look at alternatives. One alternative would be to use a fuel injector additive. This will not be as effective as a complete fuel injector cleaning, but it may help.

If you feel that you have the skills required to perform a fuel injector cleaning, read on for the step-by-step guide.

Do I Need Any Special Tools to Clean My Fuel Injectors?

This project will require you to purchase a few replacement parts in addition to the fuel injector kit. You should already own the tools that will be needed for this project. Here is a list of what you will need:

  • Tools to remove the fuel injectors.
  • Fuel injector cleaning fluid. Make sure it contains polyether amine (PEA) which is very effective at dissolving thick carbon deposits.
  • New fuel injector O-Rings.
  • Rubber hose and hose clamps.
  • Electrical leads with alligator clips.
  • Drip pan to collect spilled fuel.

Step By Step Guide on How to Clean Your Fuel Injectors

Once you have the tools and replacement parts, you are ready to tackle the project. Plan to spend about 1-2 hours on this project from beginning to end. Here are the steps you need to follow:

  1. Locate and remove one fuel injector from a cylinder on the engine. You can identify the fuel injector because it will have a fuel feed and electrical connection attached to it.
  2. Disconnect the fuel injector from the fuel delivery (fuel rail) so that the fuel injector in-flow opening is accessible. Remove the O-Ring from the fuel injector.
  3. Disconnect the wiring harness connector from the fuel injector.
  4. Connect the hose to the in-flow opening on the fuel injector and tighten with a small clamp so that it cannot leak.
  5. Connect the alligator test leads to the injector. There is no polarity required as the fuel injector will fire when power is applied.
  6. Connect one of the leads to the negative terminal on the battery. Use the other lead to touch the positive terminal of the battery when you are ready to turn on the fuel injector.
  7. Add the injector cleaner to the hose. Now, touch the test lead on the positive terminal a few times to give the fuel injector a few short sprays.
  8. Now reverse flush the fuel injector. Simply remove the hose from the in-flow side and connect it to the out-flow side of the fuel injector.
  9. Add the injector cleaner to the hose. Now, touch the test lead on the positive terminal a few times to give the fuel injector a few short sprays. This time gravity will allow the cleaner to flow back through the injector. This will remove any deposits that were too large to fit through the out-flow side.
  10. Remove the test leads from the fuel injector and reconnect the wiring harness connector.
  11. Reconnect the fuel injector to the fuel rail, slide on the new O-Ring and reinstall the fuel injector.
  12. Repeat these steps with the remaining fuel injectors.

If you followed these steps carefully, the fuel injectors should be back to original working order.

If you noticed that any one of the fuel injectors did not spray fuel or appeared to show any damage, this is the time to replace it.

Annual cleaning of fuel injectors will ensure that your car runs smoothly and efficiently for years to come.

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