Intermittent Spark

I have intermittent spark at the plug wires; compression is 123/125, swapped out coil for one I know is good, same thing. Sparks once, then nothing, motor rolls over easily, if you give it fuel, pops(occasional spark lighting fuel-I believe) but will not start. Coil, wires, and plugs are good. Seems to me, that signal is bad? Any ideas?? I know it’s getting fuel, VOS is hooked up, and fuses under side cover are all good.

Monique,   Replace the vehicle altitude sensor found behind the battery on the left side under the fuse block. Check the service manual for exact location. I think I’m close and have seen many of these go bad.   Wrench Safe, FMH

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12 Responses to “Intermittent Spark”
  1. john

    i have a 02 sportster 1200xl custom 11000 miles it started back firing on me when i would let off gas get back on it started getting bad gas mileage too. i got on it one day turn over wouldnt start i checked it was getting fuel no fire . i took it too harley shop he had it 9 mos he went through carb said it had issues well that didnt fix it he said it started every time he tried it . well i went too pick it up rolled it out of his shop tried it it started right up ran for 30 secounds died checked no fire he just shrugged . ive had one person tell me voltage reg one told me rectifier harly mechanic in tulsa told me change out ignition module id hate too buy any parts it dont need does my bike have altitude sensor

  2. Mike Reed
    Mike Reed

    I would also suggest you check the the ignition module, it is heat and cold sensitive. My bike started getting hard to start but once it was running it was good until it started getting to hope then it would shut off. It doesn’t have to be very clear to affect it anything under 50deg. will do it.

  3. Scott Tucker
    Scott Tucker

    Suggest also tracing the wires for the ignition pick up module. The harness runs from the cam housing under the engine to the control module by the fuse box or battery area. Not unusual to find a broken wire under the engine intermittently breaking or making a connection. Just a thought….

  4. Timothy frischkorn
    Timothy frischkorn

    Bought a 2000 flht used speedo has not been accurate since I’ve owned it it says I’m doing 60 actual speed is around 75 speed gap changes lower speed smaller gap

  5. randalllbonnell

    Ticket 19239 I have a 2012 FLS I have no spark. Replaced crank sensor, coil, plugs, plug wires. Still no spark. Turns over fine. Sometimes it will spark when you let off of the starter button. Only 8000 miles. We are stuck wondering if it is ECM

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