Electrical Issue - Help!

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hijacker

hijacker

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Durand, MI
Ok guys, I have an electrical issue that showed up 1 time last year and now has several times this year, so it seems to be getting worse.

I am not good at diagnosing electrical issues, so any help would be greatly appreciated.

Let me try to describe it to you as best as I can.

Stock '94.
Most of the time, the bike starts and runs just fine with no issues.
Occasionally, it won't start.

These are the symptoms...
- Turn on the key I hear the servo cycle.
- Not sure if the fuel pump clicks occur or not as this has always happened
when the bike was just recently running so the carb bowls would still be full.
- Starter turns over fine.
- Battery is strong.
- NO SPARK. I tested this by carrying an extra spark plug with me and the
next time the problem happened I pulled a cap and put in the extra plug,
grounded it to the engine, NO SPARK. Later after it started again I did the
same thing and there was spark at both caps. Tried at two different caps.
- Sit for awhile (30 seconds to an hour) and it'll suddenly just start as if
nothing had ever been wrong.

When does it happen?
- until yesterday it was ONLY after riding it non-stop for nearly a full tank of
gas. It has occurred maybe 5 times this year and I've put about 2000 miles
on it this year, so it hasn't been very common.
- Yesterday it happened about 2 miles after leaving work in the afternoon... it
died when I CAME TO A STOP at an intersection. Started right back up.
Then about another 1/2 mile and it died again WHEN I STOPPED AT AN
INTERSECTION. This time I had to sit for about 45 minutes, periodically
trying to start it, then suddenly it just started and I rode the remaining 15
miles home with no incident.

I need help on this one. It seems I have narrowed it down something that delivers spark to the coils. I'm not afraid of doing the work myself but I don't know where to start or what to test.

Any suggestions will help me a lot. :ummm:
 
Sounds like you may have a bad pick-up coil! Read the resistance when hot & not running after it shuts-off. I bet you find it's an open circuit-infinity reading. According to my shop manual, it should be between 81-121 ohms @ 68 degrees F. Some people remove the pick-up coil & subject them to a heat gun, monitoring the temp & then getting an ohm-reading once it's hot. You could also have a short in one of the wires from the pick-up. Kyle & I were talking about pick-ups, and he said he'd seen that happen. I had a similar experience to yours, 3X it left me stranded after getting to operating temp, & a check when hot showed zero resistance in the pick-up coil. Replacing it cured the issue, so look-into it. With my pick-up coil installed but unplugged I got a reading of ~99-100 ohms.

Mine would start no-problem, but after running for a bit, it would shut-off. Sometimes when it cooled it would start, sometimes it wouldn't, but it would turn-over like a champ. No signal from the crank sensor means no spark to the plugs. And I have Gannon's COP's. I also thought at first it might be the ignition box. I swapped-in a Dyna 3000, it didn't fix it. I left the Dyna 3000 in for the rev-limiter. Check out my recent thread in the Electrical section on pick-up coils. I should move on the fabrication, I coulda-had my first customer!
 
Thanks Fire-medic.

Pick up coil is #3 in this diagram correct? Or is that just the sensor?


 
If memory serves me correctly, there was thread not long ago about the pick up coil connector failing on someone's bike. This would certainly cause intermittent no-start issues. Might be worth checking this out.
Cheers!
 
hijacker said:
Thanks Fire-medic.

Pick up coil is #3 in this diagram correct? Or is that just the sensor?


Click to expand...

The pick-up coil may also be referred to as the sensor (or in the fiche, pick-up assembly), because it senses interruptions in the magnetic field of the rotor as the rotor spins on the end of the crankshaft. The rotor has ferrous bits exactly-placed in the body, and correspond to the number of cylinders of the engine, and the position of each piston. Those interruptions are analyzed by the ignition box according to the factory-loaded data for sending a pulse (pulses) to the ignition coils, which then fire the spark plugs.
 
Similar things can happen if your charging voltage is getting lower, and to the point where the battery is charged enough to spin the motor, yet not strong enough to fire the CDI box correctly. Your bike may be dying when fully warm and at the stop lights due to the CDI causing a misfire after the fan is running and voltages dropping lower.

These symtoms are mirror to my problems years ago when I finally fixed the charging, and similtaneously went to the larger battery. No other fix at that time, but I've since changed out to the newer style R/R, and I've never had these symptoms again.
 
Yes, a weak battery &/or charging system can cause similar problems too, RaWarrior's electrical troubleshooting 'sticky' is a good place to start. If your resistance on the pick-up coil is 'open circuit,' or other than the factory spec-ed 81-121 ohms when you have your problem, you may have located at least a part of the issue. That's the value for the 1990-'07 system, not the earlier one w/twin double-pickups. I don't know what their resistance is, but the online manual will tell you.
 
Check your voltage across the battery with the engine idling. You should have at bare minimum 13v or so. Since the problem seems to occur as you come to a stop, letting the rpms drop to idle, it might have to do with the voltage dropping. The vmax ignition is fussy when it comes to low voltage. Check my sticky in the how-to section for help on this.

If that checks out, I'd agree with the pickup coil theories. You have two sets of wires coming from the stator case on your 94, one bundle of three that is the stator, and a bundle of two which is the trigger/pickup coil. Check the connector on the pickup coil wires for corrosion or damage. If that's fine check the ohms as F-M suggested. Beware though, sometimes stators and coils can bench-test fine but not work right in practice which makes diagnosis tricky. I'd definitely check the ohms immediately after riding it for at least 15-20 min to get the engine to full temperature.
 
RaWarrior said:
Check your voltage across the battery with the engine idling. You should have at bare minimum 13v or so. Since the problem seems to occur as you come to a stop, letting the rpms drop to idle, it might have to do with the voltage dropping. The vmax ignition is fussy when it comes to low voltage. Check my sticky in the how-to section for help on this.
Click to expand...


Finally got a chance to start troubleshooting this problem. At idle the volatage across the battery is roughly 12.02v. At 5000rpm it increases to only 12.2 - 12.8 volts.

At this moment I'm leaning towards the r/r being the culprit. I will continue to troubleshoot the pickup coil as well though.
 
Don't forget the R/R. If the stator output tests are OK, and it is putting enough voltage towards the R/R, but not to the battery, you may have a bad R/R. Stator connectors between the stator and the R/R are also a known source of problems.
 
jfeagins said:
Don't forget the R/R. If the stator output tests are OK, and it is putting enough voltage towards the R/R, but not to the battery, you may have a bad R/R. Stator connectors between the stator and the R/R are also a known source of problems.
Click to expand...

...and the "crimp fix"............
 
Virtually any modern R/R will be an improvement. They all do the same thing in the same way, and the vast majority of powersports r/r's are made by the same company (Shindinguen?). Really the only significant difference is the physical dimensions. Can be from a harley, a snowmobile, a jetski, whatever.

The R1 part works fine but has very tall fins and is kind of hard to find a home for. The ZX14 one I used has much shorter fins and is also a MOSFET (produces less heat, so fins don't need to be huge).

If the part number starts with a "SH" it's a shunt, "FH" means mosfet. Go for the latter.
 
RaWarrior said:
Virtually any modern R/R will be an improvement. They all do the same thing in the same way, and the vast majority of powersports r/r's are made by the same company (Shindinguen?). Really the only significant difference is the physical dimensions. Can be from a harley, a snowmobile, a jetski, whatever.

The R1 part works fine but has very tall fins and is kind of hard to find a home for. The ZX14 one I used has much shorter fins and is also a MOSFET (produces less heat, so fins don't need to be huge).

If the part number starts with a "SH" it's a shunt, "FH" means mosfet. Go for the latter.
Click to expand...


Cool, thank you. I'm sitting here searching sites for the Shindengen fh001 and not able to find that exact r/r. :ummm:

As usual, the people on this forum rock. :punk:
 
Sean Morley sent me one - think it was just the newer version. It bolted right up where the old one came off, but with longer through-bolts to hold it, and it was finned whereas the OEM ones weren't. I email him from work in the AM, and darned things tend to almost get delivered before I can get home to check the mail....he's that good.
 
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