175 Johnson RECTIFIER & REGULATOR caught fire. Any suggestions what caused this?

Took the boat out to give the kids a boat ride and do a test run since it sat up all winter. Ran about 20 miles with no problems, except my Tac would quit working from time to time. On the way back the last mile to the boat ramp I opened it up for a little bit and when I came off plane the engine stated running rough. So I goosed it alittle and the engine went to a high idle then stalled. wouldn't start. Got it back home and put it in on the garden hose and fired it up and it went to high throttle. So I shut it off right away. Smelled burnt palstic so I removed the coweling and notived my timing, for lack of better word, lever was stuck in advanced position. pulled the cover to it off and and notice the retifier was sparking even with the ignigtion off. It had melted the back portion of the optical timing along with some wires and the rectifier was totally melted. So my question is. Should it still be getting power with the ignition off? What caused this? It's looking like it will be close to $600 in parts to fix it and I just don't want it to happen again.

Re: 175 Johnson RECTIFIER & REGULATOR caught fire. Any suggestions what caused this?

Re: 175 Johnson RECTIFIER & REGULATOR caught fire. Any suggestions what caused this?

I'm more familiar with the 175 crossflows with the large 35 amp alternator. Specifically-the combination rectifier/regulator. They have been known to fail on occasion. Usually they fail open. On occasion they fail closed. When that happens, that rectifier is conntected direct to the battery. They can catch on fire and there is lots of resulting smoke and smell. Sometimes the fire will damage the timer base and the flywheel magnets and the stator. Not always. Usually no damage to the engine. Word of advice on those high output alternator systems. When you start to see issues with the tach, head to a dealership. .

Re: 175 Johnson RECTIFIER & REGULATOR caught fire. Any suggestions what caused this?

Re: 175 Johnson RECTIFIER & REGULATOR caught fire. Any suggestions what caused this?

All the above and loose corroded
battery cables

Re: 175 Johnson RECTIFIER & REGULATOR caught fire. Any suggestions what caused this?

Re: 175 Johnson RECTIFIER & REGULATOR caught fire. Any suggestions what caused this?

Thanks for the input. Looked at it yesterday and my optical sensor, the recifier and the wiring to the power pack is going to have to be replaced along with various plastic pieces. Talked with my insurance agant today and they said they would cover it. A big relief cause I'm alittle tight on money right now. But thanks for the incite.