how do you know if an injector is leaking

[Roger]

How do you go about actually determining if a fuel injector is leaking gas into the engine? Is this a dealer/mechanic sort of job? My last several uoa are showing increasing amounts of fuel dilution. The car is a Nissan Maxima with the V6 engine. Thanks.

 

[brianl703]

You could use a fuel pressure gauge to see if there's any pressure loss after shutting the engine off.

 

[tackleberry625]

In my father's 1985 and 1999 F-150s, he could see and smell fuel around the injectors near the base of the intake manafold where the injector and manafold mate together. If you have a leaky injector, I would get it fixed asap because it could cause a fire. Some vehicles it is better to take it to a good dealer (if there are any in your area) to get them / it replaced because the dealer deal specifically in the type of vehicle you have. That is my opinion though. If you have more fuel getting into the engine then is needed, then it may be another problem such as emissions equipment. Is your "check engine" light on?

 

[H2GURU]

Mechanics stethescope works well for deisels. Lacking such... try a looong screwdriver and keep fingers out of the FAN.

 

[Gary Allan]

Quote:
Is this a dealer/mechanic sort of job? My last several uoa are showing increasing amounts of fuel dilution.


Well, unless you've got a very lazy O2 sensor ..I'd say that it's almost assured that you have leaking injectors. There can be other causes ..but the system should compensate rather well unless you're into only short trip usage.

Use a decent fuel injector cleaner like PI periodically and see if the condition improves. If not, and your O2 is newer, then I'd plan on getting your injectors tested and flow matched (again, we don't know the mileage/age/etc here).

There will be some other "check this" suggestions that are more attuned to your individual engine from those more acquainted with it.

 

[mechtech2]

Cold weather will show increased fuel dilution, for other reasons.
Is one spark plug different from the others? More color or fouled?
Or are you concerned with leaking when the car is turned off, and there is still pressure in the system?
Once again, checking the plugs or cylinders after a shut down will show a wet one.
A quick test is to pull the injector plugs for a moment, and see if the RPM drop is the same for all cyls.

 

[hannaco]

The problem might not be a leaking injector, rather a dirty one. If the spray pattern is not correct, the fuel can just drip out causing fuel wash down of the cylinders. That can cause the fuel dilution of the oil.
A way to check the injectors is to take them one at a time, and put them into a clear jar. Cycle the ignition and look at the spray pattern. Also look to see if you get any drips that might indicate a leak. If you see a problem, use a good injector cleaner. As suggested PI is a good one.