How to Clean a Fuel Injector

hand holding a fuel injector in an engine
  • 1-2 hours
  • Intermediate
  • 15-25
What You'll Need
Fuel injector cleaner
What You'll Need
Fuel injector cleaner

As most car or small truck owners know, a clean fuel injector is an important key to the efficient operation of their vehicle. Three common questions asked by vehicle owners are: 1) why do fuel injectors need to be cleaned, 2) how do injectors become contaminated, and 3) what can the vehicle owner do to keep his car's injectors from becoming contaminated. The information below will provide answers to these questions, along with suggestions for cleaning your car's fuel injectors.

1. Injector Contamination Causes

Carbon deposits form on the tips of your car's injectors from "coking," a process where fuel left on the tips becomes baked on by increased heat from the engine when it stops running and when the coolant stops circulating. These deposits remain on the injector tips and continue to build up each time the vehicle is heated from use, then it is shut off.

2. Preventing Deposits

arrows pointing to injector plugs in an engine

There is little you can do to prevent fuel injector carbon build-up. It is a natural occurrence that happens during the engine's operation. You can clean these deposits from the injector's tips or you can use an injector cleaner additive; but keep in mind that, although additives can reduce carbon build-up, these same additives may have a tendency to worsen deposits on the engine valves.

3. When to Clean Fuel Injectors

Frequency of injector contamination build-up is unpredictable. It is determined by the frequency of your vehicle operation. Each time you use the vehicle and then turn it off, contamination builds up more. Typically, all you can do is watch for the performance level or emissions control level of your car to begin dropping. You may be unaware of this buildup, unless you learn of it from your auto repair mechanic who runs an engine test.

4. Cleaning your Car's Injectors

car engine

To clean your injectors, be sure they are disconnected from the fuel pump and the fuel pump is disabled by removing its fuse or relay to prevent flammable gasoline being pumped out while doing the cleaning process. Also, taking your gas cap off will help reduce the chance of an explosion.

5. Attach the Fuel Injector Cleaner

Read the directions you find on your fuel injector cleaner. Then, after making sure your gas cap has been removed, the injector cleaner can be attached to the injectors. Following the directions on the cleaner, start your car's engine and allow it to run for the time recommended on the cleaner’s directions.

6. Finish

When recommended time has elapsed, turn off the car's engine, remove the injector cleaner, attach the fuel pump, put your gas cap back on, and start the engine again. Test drive your vehicle to listen for unusual noises that could be from the injectors. Pay particular attention to any unusual vibrations that can indicate that the engine is not running smoothly. If you detect any engine problems, have a mechanic check for blocked fuel injectors.