Hello;

I have been experiencing a re-occurring but not recreate-able problem with my bike lately. While riding, the bike spark for a second. Check engine light comes on, speedo drops down to 0, loud backfire, speedo jumps back upto 65 (or whatever speed i am going) and normal riding resumes for a period of time. This period of time can be between 1 second and hours. I may get 3 or 4 within 10 seconds, or just 1 in 50 miles.

There are however times where the speedo will drop down to 0, and the bike will completely lose spark. Pull over to the side of the road, dead. I can try and start it till I'm blue in the face, turns over, but does not fire. Pull a plug to see if there is spark, no spark. Then, without warning spark. This could be 30 seconds after I get to the side of the road, or 2 hours.

At first there seemed to be absolutely no rhyme or reason when it would fire and not fire. But after a bunch of times on the side of the road, I noticed that if when I turn the ignition switch on, the engine light does not come on, the bike will not fire. If the light comes on, it will immediately fire and I'm good for a few more miles till it does it all over again.

Here are the bike stats:

04 FXST, Carb, 40k Miles.

His what I have done to try and find the problem:

-Repaired frayed turn signal wire (Figured TSM and Security are tied into the same module so maybe this turning security on and off while riding). Bike ran good for a hundred or so miles then started to act up again

-Replaced coil (No spark, then letting it sit and it works, coil could be bad). 8 Miles down the road, same situation, except now I have a spare coil.

-Talked to a trusted HD service guy, mentioned that it could be an over charging issue, and the bike will shut down when it is overcharging, and by turning it on and off like I am on the side of the road i'm draining the battery just enough to get it running again. Unplugged the regulator so that the battery wouldn't charge at all, and still dies. So overcharging from the regulator seems eliminated. This should also eliminate the stator as without the regulator plugged in its not doing anything.

-Replaced, cleaned, checked, double checked, and examined all fuses and the plugs, all clean. Still Dies.

-Disconnected headlight someone told me they heard of a faulty headlight causing issues (sounded goofy to me, and proved to not be the case as it still died)

-Cleaned and wire brushed all grounds, replaced all star washers to ensure a ground was not loose. Tightened all battery connections for a 30th time, went over all wires, couldn't find anything. Same problem.

-Found a used Ignition Module (guy said it was taken off a bike that was being upgraded to an SE setup). Installed, and followed the 30 minute procedure to get the Security Module and new Ignition Module to "Play" together. Fired up, bike ran great that day, and another 50 miles the next, then died again.

At this point I am either down to replacing the battery (which is strong and has no problem turning the bike over time and time again), and again searching for a frayed wire.

The reason a loose wire seems somewhat hard to believe to me is that i can turn the ignition off, walk away from the bike for 3 hours, turn it on, and it will fire up. Touching absolutely nothing other than the switch (which i also examined for a short), not moving the bike, or doing anything that would cause a wire to jiggle.

Could a messed up cell in the battery be causing it to arc? It doesn't happen exclusively when under load either, i can pull the clutch in on a long hill and coast and it still conks out.

I could bring it to a dealer, but it will work right now, and i will end-up wasting 120 bucks for a service tech to say "we couldn't make it happen again", only for it to happen as i am on my way home.

 

Those damn intermittant problems can be a pain. You seemed to have done quite a bit of diagnosing, probably more than you mentioned. I can only add a couple items that you have already checked but it could be crank sensor, or it's wiring. The run switch contacts or it's wiring. What I've done in the past is to wiggle wires to see if I can locate a break with the engine running. Last time I had a similar case was an ultralight engine with two ignition systems where one on individual checks would quit working when hot. Turned out to be a broken wire close to the coil. Looked perfectly fine on the outside but pulling on it when cold and running it would quit. As the plastic coating expanded from heat it would seperate the copper wires inside causing an open circuit. This behaviour could also effect the crank sensor, however it will most likey be within it's internal circuit effected with engine heat. I suppose one could heat and cool it with the ohm meter attached to varify it. I don't think the battery will cause that and yes the turn signal and security module is one unit. Good luck and if you find it post what it was.
Ron

 

Thanks for the input.

CPS seems like it could be a culprit, as the bike doesn't seem to totally shut down, just the ignition system. Maybe the brain in the bike is seeing the CPS as totally failing and because of that the engine light doesn't come on, no spark, dead on side of the road.

If its not that, I am really down to just wiring somewhere, although i still have a hard time believing that a wire could expand and contract enough such that i can turn the ignition on, it wont fire, walk away from the bike for a bit, come back and it will fire 100% of the time.

There is one other thing that I just thought of that I should have thought of right away. I do have a BadLands Load balancer, which is used on the turn signals, and in turn part of the security system.

I completely cut the turn signal wires to eliminate them as a problem early on. Normally this shouldn't matter as its just like having a blown bulb, but I am wondering if combined with the load balancer that for all I know might be going bad, is causing the problem.

If its not something mentioned yet, I am at a total loss, and will have no choice but to take it into a dealer who can hook it up to a fancy 50,000 dollar HD diagnostic machine and part way with an untold number of dollars.