Hello,
working on my uncle's bike. He has a 2002 FXSTS Heritage Softail Springer carbureted model. He has had the bike in and out of several shops - including the local dealership. Every time, they say they are unable to reproduce the problem. I had him leave it with me for a couple of weeks. I have put about 60 miles on it, and had it die on me twice. Here is his original email to me explaining what has happened to this point:

"It is a 2000 Harley FXSTS with a Mikuni 45mm carb that was installed last
Sept. It has been running fine since the new larger carb was installed.
Then around June the speedo started acting erratic and quit working. I
replaced the speed sensor, but no help. Harley ended up replacing the
speedo to fix the problem. Then about two weeks later the battery died. I
replaced the battery and a week later the new battery died. I then replaced
the voltage regulator and recharged the new battery with a trickle charger.


The first time I test rode the bike after the regulator replacement is when
the bike started stalling. I was about 3 miles from home when the engine
died. It wouldn't start until I turned the ignition switch off/on. I still
had lights working.

It has continued to die within a few miles of home since. Each time I have
to cycle the ignition switch to get it to start, but it always starts right
back up. It has happened at all speeds and on straight and level roads. No
one has been able to reproduce or fix the stall when they had it in their
shop. The first shop American Bike Tailor said it probably was bad gas, but
it has had several tanks since then. Harley replaced the main circuit
breaker, but it didn't fix anything. American Cycles replaced the crank
position sensor. It ran good for about 3 trips, the longest about 30 miles.
Then it failed again yesterday about 8 miles from home."

Now, I have had it die on me twice while riding. The first time was on smooth level road - no bumps or potholes or extreme leaning involved. I pulled over to the side of the road, cycled the run/off switch and started it right back up. The second time was today - I was riding the bike back to him (thought i had it fixed - replaced the BAS sensor) and it died when I hit a rough patch of road. He has had everything replaced sensor wise that would kill the bike. As far as I know, the only sensors that will kill it are the crank position sensor and the BAS sensor. I have done quite a bit of reading on this problem. Seems like there is no consistent cause. People have had problems with everything from bad sensors to bad grounds, bad switches, bare wires, etc. I cannot get the problem to occur consistently. I can ride over some seriously bad road and it continues to run just fine. I took the control group apart on the throttle side of the bars and wiggled the wires, jiggled the switch, tried to push on it slightly, tapped on the housing, etc trying to get it to die. Did the same with the ignition switch. I have played with the wiring harness - wiggling it around to the point it goes under the tank. Nothing will cause any kind of stumble or cause the bike to die. Does anyone have any other suggestions? I would just take it to the dealership for him (they offered a $42.50 diagnostic session), but unless they can reproduce it, they cannot troubleshoot it. Their solution is to throw it on the dyno and let it run for an hour or more. But that has been done twice before with no results. I am a very competent motorcycle mechanic - especially with Harley's - but I'm scratching my head on this one.

I have checked all the simple stuff - battery cables, ground locations, etc. This last time when it died on me, I was going about 50mph, hit some bad road, and it died. All lights continued to function. It was as if I had hit the run/off switch. No sputter, no miss, just like flipping a switch. All I did was flip the switch from run to off then back to run and it backfired and started back up without having to pull over. I hit the off switch again and cycled it back to run - same thing. Lose power, backfire (from fuel being pumped into the exhaust), start back up. Please help... He really enjoys his rides, and he is afraid to get too far from his house now because of this.

 

I'd guess a intermittent short somewhere or poor connection.
I'd be checking continuity and supplied voltage.

 

Try changing out the switch. I'm an avionics tech and that seems to be a common problem with heavy vibration loosening the contacts inside a switch on aircraft. Harley's have a lot of vibration

 

Quote:
"Then around June the speedo started acting erratic and quit working. I
replaced the speed sensor, but no help. Harley ended up replacing the
speedo to fix the problem. Then about two weeks later the battery died. I
replaced the battery and a week later the new battery died. I then replaced
the voltage regulator and recharged the new battery with a trickle charger."

Seems like a great place to check for pinched, cut,altered, damaged wiring.
I had a bike repaired under warrenty years ago and found 2 wired that were pinched between the Speedo and the mount plate. Others have made good suggestions too.

 

So you flip the switch and it starts back up. Is there any way to bypass the switch and hardwire it temporarily.

 

That was my first thought - eliminate the switch. However, I have worked that switch every which way I could think while the bike was running and have not induced a failure yet. The fact that the issue started shortly after he had the regulator replaced made me focus on that area. I have looked at every connection having to do with the regulator, but have not found any issues. The bike died on me again today pulling into an ATM. I was going maybe 5mph on a very smooth surface with no lean. The instances in which this happens are not consistent. What would cause the bike to just shut off like I hit the off switch? I know the CPS and BAS would cause it, as well as the run/off switch malfunctioning. What else? Would a dead short trip the main circuit breaker? Even if that was the case, would I be able to immediately start the bike up again by toggling the run/off switch? I think isolating what could be causing this kind of failure would help localize troubleshooting efforts.

 

Mikey, I will be pulling the tank/dash tonight to look for possible pinched/shorted wires. A grounded power wire running to/from the ignition switch seems like it could cause the bike to stop running, but wouldn't necessarily cause me to have to toggle the run/off switch to get it to start again. When this happens, the bike loses power and will start right back up immediately... But only after I toggle the run/off switch. If I turn the ignition/key lock off and then back on, the bike stumbles, but continues running when i flip the ignition back on without requiring the run/off switch to be toggled. Seems like that would negate a momentary ground from a hot wire running to/from the ignition switch. Is my thinking flawed here?

 

Had something like that happen to my 06. It was the main switch, contacts needed cleaned and relubed with Die electric grease. Been great since.

 

Just a thought maybe the ECM is going south but there is no way to check it unless you know somebody that has about the same year moddle bike that you could trade or swap out and see if his does it or yours dont.

 

I was doing some more research on this and read Bout a guy that had a problem with his system relay. Is that only on EFI bikes? Is there a relay that the run/off switch powers up to supply power to systems on the bike? If so, a sketchy connection there could be causing this problem.