A riddle... No Spark after a wreck.

[fintip]

Had a wreck. Two drunks ran out into the street in front of me, then froze like a deer in headlights. Wet pavement. 

EMT said based on the distance my bike skid (yes, my pretty one...  ), I probably hit them between 5-15 mph.

I was 0% at fault, they confessed their guilt at the scene of the crime, and there was a witness.

...But my bike wouldn't start. Everything sounded good, just no attempt at making fire.

Brought back to shop. Confirm that there is no spark.

Some other clues:

Plugs are not fouled.
Fuses are all good.
FAT RED WIRE GOING TO THE KEY SWITCH IS HOT. Reeeally hot.
Collision with the pedestrians was with the front left side of bike, but it hit the ground and skidded on the right side.
All connections that I've found look good, clean, and well connected.
DCI *looks* good, circuit board doesn't show any signs of burned anything to the eye. (Anyone know the resistance tests necessary to confirm DCI function? 1990.)
Battery is solid.

And I was wearing my gear, so I'm fine. Helmet didn't even hit the ground, just skidded in my jacket.

--------------

I don't know if it matters... But this was my first time riding the bike in almost a month. I had what seemed to be overheating symptoms one day, 60 miles out of town. Bike should have had no problem keeping cool--it was hot, but not that hot, and it has the aftermarket RPM oil cooler.

Bike slowly lost power, started surging, got to the point where I could only get up to 40 going up a slight incline on the highway. The tach was also freaking out.

At first I thought it might be the DCI. Then I thought it was perhaps tight valves--the bike has always had a problem starting if it had just been shut off, and had been rebuilt not too long ago with high compression pistons and racing valve springs, would also backfire on deceleration, so I thought the exhaust valves might be dangerously tight.

Towed it back to the shop. Did a valve adjustment the same day, hours before the wreck... Once cooled down, even the same day it gave me the first presenting symptoms, it would seem to start and idle normally. The symptoms only show after a while.

Well, the valves weren't tight. I mean, 4 were borderline, one was tight. Went ahead and swapped those, synced the carbs (they were a little out, but not much). I didn't ride it much, but I felt like I could feel the beginnings of the same symptoms coming on in a 6 mile drive on the highway that night, some irregularities in power delivery and some minor surging.

So I don't know what that was, and I don't know if it was related. If it was the DCI being borderline bad (maybe heating up caused electronic parts to swell and start giving partial connection/throwing off timing? I'm stretching, but I'm at a loss here), maybe this impact could have finished it off. It's the current thing that's next on my list to test...

...but it doesn't explain the hot keyswitch wire.

[TexasDave]

Backfire on deceration indicates a very lean condition and also would contribute to hot running. Hot red wire indicates an overcurrent condition and a short somewhere. With the short, voltage to the coils would be low to nonexistant. With the bike off I would check the continuity to ground in the brake circuit. If you have continuity to ground with neither brake applied there is a short somewhere in that circuit. Check the operation of both the brake switches and the wiring around them. This is where I would start looking. Keep us up dated. Dave

[novaraptor]

Fintip, my condolences on the crash, and best wishes on resolving the electrical problem. Sorry I haven't any ideas to offer you..

[fintip]

Thanks guys. Will try some prodding today and post back if I get any more info.

[TexasDave]

Thanks guys. Will try some prodding today and post back if I get any more info.

Look for the obvious things first. Lights or switches that don't work. Wires located by the physical damage. Checking for shorts is not hard (except on women) just time consuming.  Dave

[Steve_in_Florida]

fintip!

See if the coils got jostled. Don't they ground there? I seem to recall a thinner (brown\black?) wire with a round eyelet that makes contact with the long coil mount bolt on a stock `90?

Check also the main engine grounding point for corrosion. Battery connections also. Possible damage to battery?

That's what I can throw out there.

I'm really bummed that you wrecked, but happy you're still here!

Keep us posted...

Steve

[Pat Conlon]

Hit the ground on the right side?

Hmmmm...That's the side that has the handle bar kill switch....try isolating that from the equation.

[fintip]

I'm presuming the kill switch it fine because it seems to be operating fine; nothing tries to spin with it in the 'off' position, things try to spin when it's in the 'run' position.

The coils still seem to be grounded.

Corrosion is pretty unlikely given A) the state the bike was in, and the fact that everything was out and repainted in the last couple of years, and B) not really fitting an acute onset timeline.

Battery seems fine, since it keeps spinning everything... Have also tried with supplemental power to battery, and given it some charging to cope.

Wires located by physical damage were my first idea, but nothing looked out of place. Guy very carefully ziptied the shit out of the whole harness, and I kind of wonder if he installed a new one. I've always had great connections everywhere, no dimming headlight/dash when idling. Plugs all looked nice.

[novaraptor]

Just checking to see if you found the problem, Fintip?

[Steve_in_Florida]

Wanted to add another thought: Alternator brushes.

Steve

[fintip]

So, hot ignition wire was likely a long term problem. It was hotted closest to the plug itself, and even 8-10 inches (.25 meters) away, it wasn't as warm. After controlling for some other variables, I decided the plug itself was bad. I was right. Cut the wires off the plug and tied them together by hand, no more hot wire.

Cured the hot wire. Did not cure the spark problem. (But I do wonder if this was somehow related to my 'surging' power problem from before the wreck that I described? Maybe it would get so hot that the connection would start becoming intermittent? Does that make any sense? This is the plug for the keyswitch we're talking about, blue small wire and a big red and big brown wire. The red wire was getting hot, still using the plug for the brown and blue wires, red wire is now hand tied for the time being...)

Unplugged the alternator. Did not fix the non-sparking issue or create any noticeable difference.

Battery is totally dead after sitting for a month, making me assume there's probably (but not certainly) a draw on the system, something I had previously suspected but rode too often to tell for sure.

Back to thinking it's probably the DCI. Anyone have a spare to sell?

Also, my manuals are now hidden from me. I'll keep looking for them when I get a chance, but I had been keeping them temporarily in my brother's garage. He just moved, and my stuff got mixed up in the process. 

So: does anyone have the troubleshooting procedure for the 1990 DCI handy? Resistance values I can check with a multimeter on the terminals, perhaps?

Wouldn't mind some insight that might be gleamed from glancing at the wiring diagram, either.

Thanks.

[TexasDave]

My next door neighbor did not have any spark on his prize Porche 911 so he immediately ran out and purchased a new ignition module for $500+. No spark. He asked me what I thought. I told him if I start replacing parts I start with the cheapest ones first. Recommended the coil which he purchased and fixed his problem. Get a wire schematic and test the voltage to the primary on the coils. The same circuit that supplies the DCI also supplies the coils. If you do not have any voltage at the coils start tracing it from the switch--through the fuse to the coils. The supply for the DCI comes off the stop switch(same circuit). See if you have voltage on both sides of the stop switch. Get a wiring diagram and diagnose the problem first. Dave

[pdxfj]

Try bypassing the handlebar kill switch and see what happens. Did this on someone's bike at a rally that wouldn't start and it cured the problem. One we bypassed it I was able to see the ignition pulses with a multimeter at the connectors at the coils. The coils were unplugged.

[Firehawk068]

Try bypassing the handlebar kill switch and see what happens. Did this on someone's bike at a rally that wouldn't start and it cured the problem. One we bypassed it I was able to see the ignition pulses with a multimeter at the connectors at the coils. The coils were unplugged.

I was just thinking the same thing..................That was Erich's bike...........
He had all kinds of trouble with it cranking and cranking, but no fire.................Until Garth's electronic wizardry found that it was indeed the kill switch..............

[fintip]

DCI was indeed bad.

I took a multimeter to both, testing resistance between terminals on both. Found one with infinite resistance on the bad one (no connection), that was not so on the good one.

I took a video of me touching a bunch of the terminals with a multimeter on the good one, for someone else to compare theirs against if they ever wonder if they're experiencing the same thing.

I'll put it up soon and put a link on the wiki.