How do you diagnose a stuck fuel injector?

 

Umm..you can do a residual fuel pressure test....that will atleast let you know if there really is one stuck open..

 

What is a residual test?

 

Anyone?

 

The easiest way is to use an engine stethescope, screwdriver or hose to an ear, etc and put in contact with the suspected injector while the engine is idling. You should hear the click of the injector's open/close movement. Compare to the other injectors.

 

Or you can prime the pump (turn on the key) and watch the fuel pressure. It will slowly bleed down if you have a leaky injector.

 

Good tips! Thanks.

 

Awesome work... Looking to build myself an injector test bench. Any info would be greatly appreciated if you're still happy to share your knowledge.

 

If you have or have access to a good scan tool you can do a balance test. If not then pull plugs and see which one is soaked in fuel.

FYI, if you find it, you need to rotate the motor by hand and least twice to push out any fuel sitting in the cylinder with the sparkplug out. With a stuck injector (most likely open) you have a 90% chance of hydrolocking the motor, bending a rod or worse. Seen it a few times.

Once you find the culprit, you can remove it and if you can blow through it, it's really bad. I have a few here in my "catastrophe box" that I keep for fun discussions.

 

get a pump, filter, regulator, signal generator ($10 off aliexpress) and a "mosfet driver" for 15-20 amps continuous. use a flyback diode. i have 1/100 gram scale to determine the fuel mass. oh, and connectors for the injector, i just use spades.