Troubleshooting electrical/fuel problem

[Niceboxer]

This past weekend my '02 1100S (36k, single spark) stalled out 2 blocks from home on the way back from a short 5 mile ride. Granted the bike is just about due for a valve adjustment, but something about the stall didn't feel right. The engine didn't even try to idle, it just went to sleep as I dropped the bike in neutral for a stop sign. The engine did start back up hesitantly, and was good enough to run me back home, but on the way, I did notice that the instument cluster illumination was a little dim, and the left turn signal indicator was glowing faintly. So I guess there was something electrical going on (duh).

I parked the bike and looked for obvious signs of a short (smell, burnt wires, etc.) but didn't see anything. Fuses are all good. Turned the ingnition on, and heard the fuel pump run for a second, as usual. Dash was brightly illuminated and the ghost in the turn signal loop was gone too. Tried turning it over with no luck. Then I see fuel dripping from the exhaust headers at the connector at the cross-over pipe in front of the alternator cover.??

I pulled the plugs, and both were black. And dripping with fuel. Got a fresh set of plugs and confirmed spark at both sides. Tried starting again with no luck.

So my question is, what would cause the injection system to dump fuel into the cylinders to the point where it would overflow into the exhaust? Is this probably a symptom of a burnt ECU?

Any thoughts?

Thanks,

Anthony

[Guest24]

Check battery connections and strength first. If it staled at idle, I'm saying it's the battery or connections

[jduke]

Sounds like the battery is gone. Raw gas will damage your O2 sensor, so don't be surprised if you have upper rpm problems once you do replace the battery.

[Dr. Curve]

VERY RARE.........but it did happen to me once on a then new, K100RS. The injector stuck OPEN.......raw gas starting coming out the exhaust and I thought I would be looking like a german flame thrower before I could get it home. I wrote Richard Dampf about it at once. They warrentied four new injectors and installed them right away. Never seen this again. If your injectors are squirting instead of misting.....raw gas will be present, carbon soot will be present, and it will be hard to start...........fire is a danger. Perhaps its a grounding problem or a battery as has been suggested.

[roger albert]

Battery or connection wires at base of key switch, or other loose connection first.
Dr. Curve's advice is good on the injectors (I've seen it too) but your dim lights imply an electrical issue first. Get the electrics sorted and fresh plugs in there, and if you still have problems, then look into the injectors and fuel system.

Raw gas will damage your O2 sensor, so don't be surprised if you have upper rpm problems once you do replace the battery.

Right and very probably wrong. Yes, the raw gas is tough on the sensor, but no, it doesn't normally cause a high rpm problem. On the contrary, is causes a low-load/low-rpm/steady-state problem, since at high throttle and rpms, the sensor input is irrelevant anyway.

[R111S]

Alternator belt broke?

[Niceboxer]

I'm thinking battery as well. New one is on the way.

If that doesn't help, I'll chase after connections and alternator next.

Thanks all.

[Niceboxer]

Delayed update: Turns out it was the Motronic unit that was fried. Who knows if it was the aftermarket FIM chip that fried, or the Motronic board itself. Either way, it was probably a 1/8" phono plugs on my Auto-comm unit that jiggled around and found a way to ground and short on the exhaust.

I picked up a used stock Motronic unit with the exact same part number (presumably from another Boxer Cup Prep) and it plugged and plays just fine. Not even sure if it runs any differently with the stock ship than it did with the aftermarket chip. No real difference in backfiring or performance that I can tell, but admittedly I'm not doing track time.

Lesson learned: stick with OEM (unless your N8).

TG

[Guest24]

That's a new one, indeed. I'd like to know why you suspect the Autocom lead since I have that system on my RT. Also. if the FIM chip was defective, why did it take so long to trash the MoTronic? I doubt this was the case. I really wonder if you got a voltage spike from the alternator regulator. Have you replaced the battery lately? Or maybe it's the simplest reason of all, chit happens.

[PFFOG]

I would check the above mentioned connections and grounds, a voltage spike from another electrical issue could have fried the ECU. The Inst and signal lights don't seem to fit an ECU failure.

[Niceboxer]

BTW, I forgot to mention that I did get a new battery to no avail before replacing the ECU. Don't think the old battery was bad.

The only reason I suspect the Auto-Comm input lead is that I found the jack resting on the exhaust middle pipe under the seat, with the jack housing melted to where the wiring pins were exposed. And the Auto-Comm was hard wired to the bike's electrical. But I fully understand the skepticism in defense of the Auto-Comm. Not sure where the + signal would have come from (since the unit was not in use at the time) to create a short.

Regarding the FIM chip, I don't think it was defective, since it ran fine for 10's of thousands of miles. It was either the weak link when there was a short/spike, or maybe it just reached the end of it's life. I have to assume that a microchip has a limited lifespan, particularly in a high-vibration environment. And that an FIM chip is not the same as a Bosch (or whoever makes the chips for them).

Truth be told, I did not put the FIM chip in the new ECU to see if it was the chip or the old ECU that was bad. Didn't want to find out that it was a bad chip that fried the board. All I know is that new ECU with stock chip works fine.

I'll keep en eye out for other possible shorts, though.

Thanks all.

TG

[AZ-Twin]

How was the faulty ECU diagnosed?

[Niceboxer]

Faulty ECU was diagnosed by process of elimination. Bike didn't run with the original ECU (with FIM chip), and ran fine with the replacement used one.

According the service manager at the local dealer, the fault codes from the old ECU would not have been informative(?). Something about older versions of the Motronic units not really having OBD, but just spitting out codes that they don't know what to do with in most cases.

[jduke]

Sounds like BS to me.
The motronic unit they replaced has the same part number as the one they say is defective yet they don't know what to do with the codes???
Sounds like the are great "swap out mechanics".