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Latest post Sun, Jul 16 2017 3:26 PM by usironhd. 7 replies.
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  • Fri, Jul 14 2017 9:20 AM

    • usironhd
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    • Joined on Fri, Jul 14 2017
    • Posts 5

    Motor cuts out sporatically---Tach problem?

     I have a 1996 FXD.  I have a problem, that I encountered back in 2001, recur now.  When riding after a few minutes, the bike will simply shutdown and then mysteriously restart and then shutdown again, etc.  When it shuts down, the Tach needle will be buried at max RPM (but the engine is really shutdown) and then the bike will return to performing normally with a proper Tach reading.   It is as if the ignition switch was simply turned off momentarily and then turned back on.  The bike will slow down since the engine is basically off but will restart after a 1-3 second delay.  I had this problem for a short period of time back in 2001 and, after testing everything (every test proved no problem) I asked my local dealer at the time.  Their answer was a potential problem with the Tach.  When the problem simply disappeared, their answer was a "gremlin in the electronics".  The problem has never recurred in the past 17 years but just recently I experienced it again.  Do you have any idea of what could be causing the problem and how to test for it?  I have all the shop manuals for the bike and don't see anything about such a problem.  Thanks

  • Fri, Jul 14 2017 10:36 AM In reply to

    • Ironhead
    • Top 10 Contributor
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    • Joined on Tue, Mar 21 2006
    • Near Sunset at Sunset Beach, O'ahu, HI Oct 23, 15
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    Re: Motor cuts out sporatically---Tach problem?

    usironhd - first, welcome to the forums - what part of the country are you from?

    Have you done anything to the bike recently?  backtracking what was done might point a finger.

    If you check the wiring diagram in your shop manual, I think you should find that the tach is just an output from the ignition system, not an input (most tachs are just an output) - you could try un-plugging the tach and see if the problem goes away.

    I am thinking it is more likely an ignition box issue or a couple of wires which are shorting out - both are hard to trace.  Knew a fella with a custom build whose bike would shut off every now and then - 3 different shops couldn't find the problem - turned out the main wire to the switch was broken inside - most of the time the wires were connected and sometimes they would separate.

    Another thought that might shut the bike off (but not explain the tach) is the vacume line from the intake to the tank - no vacume means the petcock doesn't let fuel through.

    Let us know how you make out.

    The first tool out of the box should be the "book"  Geeked

  • Fri, Jul 14 2017 10:44 AM In reply to

    • FX
    • Top 10 Contributor
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    • Tonawanda NY
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    Re: Motor cuts out sporatically---Tach problem?

    I would have the coil load tested...The tach is related to when the coil fires...

    FX

    Don't force it, get a bigger hammer.

  • Fri, Jul 14 2017 11:22 AM In reply to

    Re: Motor cuts out sporatically---Tach problem?

     good morning. it also might be a problem inside the ignition module itself, if i remember correctly, the tach feeds off the pink wire on the module harness.

     

  • Sun, Jul 16 2017 10:00 AM In reply to

    • usironhd
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    • Joined on Fri, Jul 14 2017
    • Posts 5

    Re: Motor cuts out sporatically---Tach problem?

     It does, position 4 off the module to position 7 on the main harness.  What I can't figure out is if it is a module problem, why wouldn't it show up more frequently than 17 years and why the tach needle goes to max rpms when the ignition shuts down.  I drove the bike yesterday without one single problem after riding it a couple of weeks ago and having problems 3 times in a row.  I've previously had the coil tested and it is OK.  There's another wire, orange, that comes off position 6 of the main harness to the tach that also goes to the fuel gauge.  If this problem occurs again, I'm going to see if the fuel gauge is also affected at the same time...haven't done that yet.  If it happens again, I guess my next best step is to test the ignition module.  Thanks for your input.

  • Sun, Jul 16 2017 10:04 AM In reply to

    • usironhd
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    • Joined on Fri, Jul 14 2017
    • Posts 5

    Re: Motor cuts out sporatically---Tach problem?

     I live outside Fort Worth, Texas.  I have planned to unhook the tach if the problem arises again.  Yesterday I rode and had no problem at all.  When it happens, the recovery is so fast that you really don't have time to "real time" unhook the tach and see if that solves the problem.  I'm going to try a few other things but was really hoping someone had experienced this exact problem and had a direct solution....that doesn't seem to be the case.

    This is not a fuel starvation problem like a plugged vacuum line....I've seen that happen to others before especially after having their tanks repainted and the vacuum port was not taped off before painting.

    Thanks for your input....I'll keep looking for a solution.......

  • Sun, Jul 16 2017 12:32 PM In reply to

    Re: Motor cuts out sporatically---Tach problem?

     something else just came to mind, do you have a key ring hanging off the ignition switch? if so, the key ring can cause the switch to wear, and the swinging motion of the key ring can cause this problem by momentarily moving the switch to the off position

     

  • Sun, Jul 16 2017 3:26 PM In reply to

    • usironhd
    • Not Ranked
    • Joined on Fri, Jul 14 2017
    • Posts 5

    Re: Motor cuts out sporatically---Tach problem?

     I don't have the key or a key fob hanging from the ignition switch.  the switch positions are very positive from one position to another.  Thanks for the second perspective.  I'm going to try to ride tomorrow to see what happens.  Again, thanks for your help....

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