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Hi 2nd question since joining, our 912 uls lost spark on number one top wire,the other wire from the same coil - does - spark,engine only has 50 hours on it,so we installed a $400 dollar coil with new spark plug wires with it and swapped out the 2 ends, checked the spark plug ends - 5 ohms resistors and are 5 ohms but swapped anyway.  

      Swapped out the 2 boxes on top of the coils with each other, the number one top wire has no spark while the other wire sparks fine, and the plugs are soot black, cleans right up with brake clean and put those plugs in next cylinder and they fire just fine

     So it is pretty odd that only one out of two spark plug wires in same coil does not spark, any ideas would be really appreciated

               Thank you 

 

 

 

 

 

 

  • Re: Number one cylinder no spark

    by » 3 months ago


    As non of the Gurus have responded to you, I will do my lowly best.

    Starting at the spark plug end;

    Defective plug - it seems you have tested for this and found the plug(s) to be A1

    Defective cap- can be caused by manufacture/assembly defect, overly rough removal causing damage, poor seating. Continuity failure - check using multi meter - be sure to wiggly & twist the cap (simulating engine vibration,torque movements & air blast) as you check.

    Defective HT Lead - can be caused by manufacture/assembly defect, using lead to remove cap causing damage.Continuity failure - check using multi meter - be sure to wiggly & twist the cable as you check.

    Modules (Black box)- sorry no wisdom here - They are a capacitor discharge set up. Sealed no repair possible.

    If Module delivering spark on other plug  , I would assume that the rest of the system - charge, ignition trigger (fly wheel housing) wiring harness and connections all good.

    Refer to Heavy Maintenance Manual Section 74-00-00 for more/better insight.

    "Trigger coil assignation (on the 912 Series)

    Trigger coil A1/2 serves the top spark plug of cylinder 1 and 2

    Trigger coil A3/4 serves the bottom spark plug of cylinder 3 and 4.

    Trigger coil B1/2 serves the bottom spark plug of cylinder 1 and 2

    Trigger coil B3/4 serves the top spark plug of cylinder 3 and 4."

     


  • Re: Number one cylinder no spark

    by » 3 months ago


    I'm guessing a damaged cap.


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