Injector Maintenance and Cleaning

Although it is not the problem it was back in the early to mid '80s, fuel injector restriction is still an issue which needs to be addressed from both a preventative maintenance and repair viewpoint.

The best method of injector maintenance is continuous use of high quality fuels with a level of detergency adequate to keep the injector nozzles clean. It is also prudent to offer injector cleaning service using the Toyota approved injector cleaning system and solvents. This service can be offered whenever the vehicle is in for major service to maintain good engine performance and reduce the possibility of expensive injector replacement due to nozzle build-up.

It has been established that engines using hole type injectors tend to have fewer problems with fouling than those with pintle type injectors. It has also been established that use of low quality fuels which lack adequate detergent additives can lead to injectors which become flow restrictive or which develop poor spray patterns.

When an injector becomes flow restricted, the volume of fuel delivered for a given injection duration will be reduced. This condition will cause lean driveability problems like stumble, hesitation, backfire and surging, especially during open loop operation.

When an injector develops a poor spray pattern, fuel is not atomized and vaporized properly. It is entirely possible that the correct volume of fuel will be delivered to the intake manifold, however, this fuel will enter the cylinder as liquid droplets and will not burn. This condition will cause increased hydrocarbon emissions and lean driveability problems just as if the fuel delivery were lean. The symptoms of poor spray pattern can be very similar to those of flow restricted injectors.

When it comes time to diagnose these two problems, the recommended procedure is to remove the injectors from the engine and bench flow test each injector using the following tools. This procedure is covered in detail in the appropriate repair manuals.

The following information covers the general test procedure.

Tool Name

SST Number


Filter union and hose


Adapts fuel filter on vehicle to test apparatus

Pressure regulator union


Adapts regulator on vehicle to test apparatus

Union and clamp


Adapts removed injector to test apparatus

Test harness


Jumper +B to FP terminal

Test harness

#09842-30020 #09842-30040 #09842-30060 #09842-30070

Makes electrical connection to injector

Graduated cylinder, minimum 500 cc volume

NPN, purchase locally

Measure fuel delivery

1) Assemble SST as shown below.

Army Throwing Antenna Tree

2) Using correct inspection harness, energize injector for specified number of seconds. Observe spray pattern and compare relative fuel delivery volume with specifications.

Caution: Do not create sparks near fuel Injector and graduated cylinder. Keep fire extinguisher nearby while performing this test.

Spray Patterns Fuel Injectors

Was this article helpful?

0 0
Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

Get My Free Ebook


  • renato
    How to clean the injectors on a 1997 toyota land cruiser?
    1 year ago
  • Simon
    How can i test if fuel injectors are spraying properly on 2000 toyota sienna?
    1 year ago
  • elias
    How to clean injectors on 2017 toyota sienna?
    8 months ago
  • ponto goodchild
    How to clean injector nozzle of a toyota surf ssrx?
    1 month ago

Post a comment