Testing fuel injectors

Still trying to track down issues with the engine. Here is how I tested my new injectors just to be absolutely certain they were not the problem.

I simply took out the intake manifold and removed the fuel rail from it. I also picked up the pictured graduated cylinders from a local lab surplus store and placed them under the injectors as shown.


One of the great things about the Megasquirt EFI system is that it allows me to run the injectors at a set pulse width for a set amount of time. I could also pick which injector to test if I had a sequential fuel injection system, which I don’t; but I can chose which bank to test. If you look closely at the picture below, you can actually see the fuel shooting out the injectors…


After I collected what I felt was enough fuel, I could compare the amount that was injected.


I discovered that the injectors were more accurate than the cheep graduated cylinders I purchased…

The injectors are good, my search for whats wrong continues. At this point, I have narrowed it down to either bad lifters, (which I doubt because they would probably make some noise if they were collapsed) or a hard to diagnose problem with the ignition. It would make my life a whole lot easier if I had an old school automotive¬†oscilloscope to help test the ignition. If anyone knows someplace that has one in the Chicago area, I would be happy if you could let me know…

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2 Comments to "Testing fuel injectors"

  1. Memba's Gravatar Memba
    July 5, 2015 - 1:21 pm | Permalink

    Oh very nice test. I work for 3 years with fuel injectors but never heard about such method. Thank you. I will try it.

  2. Luke Yancey's Gravatar Luke Yancey
    August 8, 2016 - 8:54 am | Permalink

    That’s crazy that the injectors are more accurate than the graduated cylinders. The cylinders you posted are cylinders that I have used all throughout my undergraduate chemistry courses. This says a lot for the injectors!

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