Cleaning Dirty Fuel Injectors

Dirty fuel injectors have become a big selling point for popular fuel additives and gas companies. A few gas companies say that they add chemicals to their fuel that will help keep your injectors clean and make your engine run better.

Picture of fuel injection cleaning kit

Fuel Injection Cleaning Kit


Some companies selling fuel injector cleaners state that they will increase fuel economy and restore engine power. All of the above statements may be true if you actually have dirty fuel injectors.

Before you pay more at the pump for gas or go out and purchase additives and cleaning solutions it would be nice to determine if they are actually needed.

Testing the flow rate and the efficiency of the injectors can not only be performed but can verify whether cleaning is necessary. I have more information on fuel injector testing on my you fix cars website.


Testing fuel injectors

Picture of port fuel injectors

Port fuel Injectors

If an injector has completely failed electrically or there is a problem in the control system no amount of cleaners will solve the problem. You can do some basic checks to verify if the injector is operating properly.

A fuel injector is nothing but a on and off solenoid that allows fuel to flow on command. When the injector opens and closes it makes an audible clicking sound. In the old days injectors were quite loud and easy to hear.

On some newer vehicles you may have to use a mechanics stethoscope and place it on each individual injector to hear the clicking sound created by the opening and closing. If you do hear the clicking on each injector at least you know the electrical side is performing correctly. Injectors that are not being fired will not click.


How to injector cleaning

Each fuel injector should flow about the same amount of fuel as the others. This is known as injector balance. If you have verified that there is an imbalance in the fuel flow in between injectors cleaning or replacement may be required.

The metering holes in the injector tips are drilled to precise specifications. You never want to use a wire brush or other cleaning utensils to try to unblock an injector tip. The basic idea for cleaning fuel injectors is that some type of cleaning chemical is run through the injector as an attempt to remove deposits or gummy build up.

One of the most effective methods is to replace the fuel supply with a strong cleaning solution. In this case the vehicle’s fuel pump is disabled and an alternate supply of cleaning solution is supplied. Many automotive parts store sell pressurized containers of this type of injector cleaner with a hose that connects to the fuel rail.

During the cleaning operation the engine runs on this pressurized container of fuel/cleaner. You will have to carefully follow the instructions on the cleaner solution because often they recommend that you Pinch off the fuel return line to stop the cleaner from flowing back to the gas tank.

Although this method can be time-consuming and in some cases complicated it is much more precise than adding fuel injection cleaner to the gas tank to be run over a long period of time.

After fuel injection cleaning

Note that after successful fuel injection cleaning that your engine may not seem to run right for several drive cycles. This can happen because your vehicle’s computer has a learning memory. It may have already compensated for the dirty injectors as much as possible.

With successfully cleaned injectors fuel flow is returned to normal but the memory of the computer will have to catch up to this new condition. How long this will take will depend on the year make and model of the vehicle. In most instances this learning process will take only a few minutes or drive cycles.

This next link takes you back to the blog homepage from this page about cleaning dirty fuel injectors.

3 comments

  1. I am trying to find a pressurized containers of the type of injector cleaner with a hose that connects to the fuel rail.I live in New Jersey. The car is a 1990 Lumina 3.1 Liter. I have owned it since new. It runs fine at part and full throttle all temps but when warms up, idle hunts and it may stall. I have tried every sensor, IAC, tuneup, exhaust sys not restricted, so the only thing left is cleaning the injectors. It has 275,000 miles.I have gone to all the popular Auto Parts Stores, NAPA, Auto Zone, Pep Boys etc etc, so perhaps you know what stores sell this pressurized fluid.Thank you so much for your help/

  2. Hey Sal: I wrote an article about testing fuel injectors. At the bottom of that page is a link to a pressurized fuel injection cleaning kit on Amazon.I should mention the most common causes of the hunting idle condition you speak of would be a vacuum leak. The 3.1 is known for this problem from either the intake manifold itself or if your lucky the vacuum tee’s that attach just behind the throttle plates.

  3. You know Sal, one other thing you might try a lot of people over look is that if your car has a throttle plate. the adjustment gets worn and will try to starve it of air, and you say you have 275 thousand miles on car. a 18Th inch tweak with that set screw could fix that issue. car may idle little high few sec. computer will compensate for the differences hope this works for you…it worked for me.

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