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Rebuilt Fuel Injectors Not Firing?

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    #1

    Rebuilt Fuel Injectors Not Firing?

    I know this sounds crazy, but bear with me for a second. I had sent out 6 stock M20 injectors to be rebuilt last month. They supposedly tested out okay after the rebuild.

    Fast forward to this week. Just finished installing a fully rebuilt engine into the Spec E30 car I'm building. Go to start it: good oil pressure, good spark, no fuel.

    Fuel pressure checks out fine and return line is clear.

    Jump to the electrical side of things. Ohm'd out the harness before and after the C191 connection. Everything checks out 100% between the DME and C191. Continuity to ground wasn't great after the C191 for each injector terminal. However, each injector is getting a full 12.5 volts to the proper terminal.

    So the C191 seemed a bit sketchy. Cleaned that up as best we could for now by inserting jumpers between the 7 pins. Continuity to ground is good at this point.

    Still the injectors will not fire. But they seem to be getting everything they need to work.

    Pulled the injector harness off and ran +12v straight to Injector #1 and directly grounded the other terminal. Injector did not click as it should have. Repeated the same test with the other 5 injectors. No response!

    Now I have six other well used M20 injectors sitting in a spare manifold on the bench. Decided to repeat the same exact test with them, feeding them directly from a portable battery pack. All 6 clicked audibly as they should.

    What gives? I provided exactly the same scenario to all 12 injectors, but the 6 in the car will not fire. Are they bad or am I missing something?

    Thanks for any help, I need this car back together and running ASAP.
    '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black
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    #2
    I should add that the Bentley specifies an injector impedance between 14 and 17 ohms. The rebuilt ones check out at 16 ohms each.
    '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

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      #3
      If you connect the injectors to an external battery and apply voltage, it should click. The fact that you tested your old ones and they click telling me that there is something wrong with the rebuilt injectors. Since all 6 behaves the same, there might be one bad common part. Send them back to the builder.

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        #4
        I will definitely inquire with the rebuilder. Granted I don't know exactly what work he did, but I would assume he mostly performed "mechanical" work to them and didn't do anything to them in an electrical aspect.
        '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

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          #5
          Sure enough, the engine fired right up when I swapped out the injectors.
          '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

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