YAMAMAN1964
New member
Hi Guys, I have had dozens and dozens of Yamaha's, 2 strokes, 4 strokes, name it. This sled has me completely stumped.
My son picked up a 1989 VK540 to use ice fishing. Nice clean sled, started right up, drove it around, no problems.
Brought it fishing the first day, sled started, ran out on the lake about 300 yards and shut down. Let it sit 5 minutes, started right back up and run for a bit, cut out again. brought it home, got it to do it right in the garage. Checked stator, all resistance checks OK, checked grounds, wiring, kill switch, ignition switch...concluded it must be the CDI box cutting out. Replaced it, same thing. Again checked grounds, wiring, switches, etc. again. At this point, regardless of the stator ohms readings, I replaced it (All parts were from Yamaha, no aftermarket junk). Sled started right up, ran in the garage 15-20 minutes, took it outside, ran around the field another 15-20 minutes. Ran excellent no issues. It was shutting down before in 5 minutes. We figured we had it.
Brought it back to the lake the next day, sled ran 300-400 yards after running for a while warming up, and then shut down. This time for good. Did not start after sitting. Brought back to garage, again checked all switches, stator resistance, grounds, and even ran extra grounds to the frame to be sure. This is where I sit, stumped. If I knew what the signal to the CDI box was supposed to be from the stator that may help. I even tried plugging the original CDI box back in. Still no spark. Any help or suggestions will be greatly appreciated. THINK SNOW, THINK YAMAHA...
My son picked up a 1989 VK540 to use ice fishing. Nice clean sled, started right up, drove it around, no problems.
Brought it fishing the first day, sled started, ran out on the lake about 300 yards and shut down. Let it sit 5 minutes, started right back up and run for a bit, cut out again. brought it home, got it to do it right in the garage. Checked stator, all resistance checks OK, checked grounds, wiring, kill switch, ignition switch...concluded it must be the CDI box cutting out. Replaced it, same thing. Again checked grounds, wiring, switches, etc. again. At this point, regardless of the stator ohms readings, I replaced it (All parts were from Yamaha, no aftermarket junk). Sled started right up, ran in the garage 15-20 minutes, took it outside, ran around the field another 15-20 minutes. Ran excellent no issues. It was shutting down before in 5 minutes. We figured we had it.
Brought it back to the lake the next day, sled ran 300-400 yards after running for a while warming up, and then shut down. This time for good. Did not start after sitting. Brought back to garage, again checked all switches, stator resistance, grounds, and even ran extra grounds to the frame to be sure. This is where I sit, stumped. If I knew what the signal to the CDI box was supposed to be from the stator that may help. I even tried plugging the original CDI box back in. Still no spark. Any help or suggestions will be greatly appreciated. THINK SNOW, THINK YAMAHA...
opsled
Active member
Ignition coil ground? Have you bypassed TORS and unplugged ignition/kill switches to eliminate them as a possibility?
opsled
opsled
sounds like the coils on the stator where breaking down and now have totally failed. my dad had an et250 that would cut out once it got hot. did everything but stator and it still did it when my dad got rid of it. i have seen stators test good cold but when you heat them up, they would open or short and fail on an ohm test.
YAMAMAN1964
New member
UPDATE: I have tried bypassing the switches and tried grounding the base of the coil and the motor too. Here is what is interesting and a new discovery. There are 2 tan wires that go to the CDI and stator that provide a ground to kill the ignition when the ignition switch is off or the kill switch is pressed. When I disconnect that tan wire to the stator and I ground the wire from the stator, then sled starts and runs and idles, but does backfire on acceleration. This is the same wire that should kill the motor if grounded...ugh...
Sorry to drag up this old thread, but do you have an update on this issue? I’m having a spark issue with a VK540 and was wondering if you ever solved this one.
I bought the sled cheap knowing it had a spark issue. Previous owner says he tried a different Cdi and ignition coil from a working sled. I found a service manual online and Resistances on ignition coil also test good, although one plug cap did seem failed (infinite resistance). Resistance of flywheel coils test good all kill switches bypassed (i think)or at least checked for operation with a multimeter per the service manual in the case of the throttle switch and handlebar kill switch. The wiring does seem to be a mess under where the exhaust can is. It looks like it was melted at some point, with some replaced. Looking at the schematic in the service manual, I think it everything that should be connected to get spark is (I’ll go back and fix the rest of the wiring once the spark issue is fixed). Anyone have any ideas of what to try next?
Even though the resistances of the source and pulser coils are good could there be something else going on in there? The brown wire from the source coil is cut on the wiring loom side of that plug. Is that an issue? Schematic shows this going to the key switch and it’s grounded when it’s in the off position.
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jjmoneysauce
Member
Have you unplugged your TORS from the carb and shorted back the harness side?
What you are describing sounds a lot like a switch issue.
What you are describing sounds a lot like a switch issue.