Hi, I'm new to this forum, and a friend recommended that I to come here and possibly seek some advice or help. I have a 1995 Yamaha 250 (carb model) that runs great until I use it to troll for several hours. Once you are done trolling (1200-1400rpm) and try to put the boat on a plane, or go to full throttle, it misses on one of the cylinders. Once the engine cools down after a couple of hours, it runs fine on all cylinders again. If I don't troll with it, and run at higher rpm's, it does not develope the miss, and runs great all day. On one of the times that it started missing, I raised the engine, and installed new plugs, and it ran great. Figured it was the carbs causing one or more of the spark plugs to foul, so I had them cleaned and rebuilt. The next time out trolling, the miss came back. This seems more like an electrical problem or short of some sort, as the temperature runs a little warmer when trolling, (which is normal), the miss develops but does not develope during higher rpm's. I have checked compression, the stator, had the carbs cleaned and rebuilt, installed new plugs, and checked oil consumption, all are good. Anyone ever have this experience? Thanks in advance!
