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More Ways to Check Fuel Injectors

fuel injection test kit
Fuel injection Test kit

I have written about fuel injectors on many occasions and even included instructions on how to do what I consider is one of the best tests. This would be how to perform an injector balance test. Having a fuel pressure gauge mounted up and firing the injector while physically seeing the pressure drop is in my opinion the best way to check a fuel injector.

With that being said not everybody has fuel injection test kit with a pressure gauge and an injector driver. Plus on some vehicles mounting these two testing devices can be difficult. There are several other ways to check fuel injectors.

Remember a fuel injector is nothing more than a solenoid actuated fuel valve. Its operation is quite basic in that as long as it is held open and the fuel pressure remains steady it delivers fuel until the solenoid valve is closed. A fuel injector that is not opening and closing properly can cause hard starting poor fuel economy and other engine problems such as hesitation or rough running.

This boils down to whether the injector is having a hard time opening and flowing the fuel or if the injector is having a hard time closing and shutting off the fuel (dripping).

Another way to check fuel injectors

Believe it or not you can use a mechanics stethoscope to check fuel injectors. This is known as a sound test. This is quite handy if the injectors electrical leads are difficult to access and a power balance test which is also recommended is difficult.

mechanics stethoscope
Mechanics Stethoscope

You can start the engine and use the mechanics stethoscope to listen for the correct injector operation. What do I mean by this? A good injector makes a rhythmic clicking sound as the solenoid is energized and de-energized several times a second. If a thud is heard instead of a steady click chances are the problem injector has been found.

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On a six-cylinder port fuel injected engine there are six separate injectors. On most models they will be mounted near the intake valve on the cylinder head. You can move your mechanics stethoscope from injector to injector and more importantly then the clicking is that they all sound alike. In fact they should all sound exactly the same.

multi port injector
multi port injector

If a soft click or thud is heard instead of a snap click, cleaning or replacement might be in order. If an injector does not produce any clicking noise the injector connection wires should be checked and a signal from the electronic control module should be tested with a noid light.

If a fuel injector is clicking sometimes and not others the injector plunger may be sticking. This may be a sign of an injector that is beginning to fail. When there is absolutely no clicking from one single injector it is either a malfunction in the control circuit or completely failed part.

You can use an ohm meter to check for the total resistance before spending the money on a replacement part. Each manufacturer has a resistance specification but if the fuel injection windings are open (common on failed parts) the automotive meter will read infinite resistance or out of limits.

Lots of people think that their fuel injection might be the root cause of all of their problems and sometimes it is. But these problems can be verified with some diagnosis. Online auto repair manuals can supply these diagnostic tree charts. If you would like to see more posts to this site this next link brings you back to the auto repair information blog homepage.

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