Faulty Coil?
in 912 / 914 Technical Questions
11 years ago
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by Rob Seaton » 10 years ago
Rex, can you expand on this? I don't understand how this can happen:
"When the faulty A switch is on, and switched off while engine running, there is a typical mag drop, even though it wont run the engine"
Thank you said by: Rex Anderson
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by Rex Anderson » 10 years ago
Yes, initially I swapped the 6pin connectors entirely, and the problem then moved to the other switch/circuit. Then I replaced them to original configuration, de-pinning only the red leads, and swapping them alone into the opposite position....the problem still switched to the other switch. According to the Rotax manual, this points to the stator, eliminating the modules/and switches. I returned them to the original positions. I was totally surprised to find that when I was continuing to test the circuits, that when I had both switches in the ON position, the engine ran smoother, and when the faulty side A, was switched off, that I had a mag drop that looked just like normal, yet when the B switch was turned off, it always killed the engine. Clearly, the A side was contributing an intermittent spark, yet would not sustain on it's own. When I tested all plug leads with the inductive timing light....1,3 top, and 2,4 bottom had intermittent, or less than optimal feed. Plugs 2,4 top were totally normal, as were 1,3 bottom. Not what I expected, as I thought all the faulty firings were going to be attributable to the A side. Hope this is not too confusing.
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by Rob Seaton » 10 years ago
Take a look at the trigger coils: check gaps first, then resistance from pin to pin (in six pin connector).
- You have eliminated the stator as when you switched the red wires back to the original position the problem did not follow.
- That leaves the triggers and the mag switch as suspects, and you have already eliminated the switches.
Thank you said by: Rex Anderson
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by Rob Seaton » 10 years ago
The symptoms really sounds like a trigger gap problem.
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by Rex Anderson » 10 years ago
Rob, The problem DID follow the power lead from stator for the A side. Whichever 6pin connector the "A" red lead was in, became the side that would not sustain the engine. Could it be intermittently shorting to ground? thanks for helping!
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