I started having problems last time I took my boat out, 70h.p merc. It was stalling when I put a load on it. I changed the spark plugs and still no difference. After grounding out my coils on all three cylinders one at a time, #3 was the one that made no difference to the engine. I removed the coils and checked the impeadance on all three. They all measured the same. I've checked my compression, 110, 112, 115,. I changed the switch box 450.00 dollars later and still #3 makes no difference to the engine when I ground out the coil. Also I cleaned the carbs this spring as a result of old gas gumming up the needle and seat. I removed the carbs and soaked them in QuickSilver power tune engine cleaner,as per the dealer suggested. And when I put it back together it ran great. Also when I pulled out spark plug #3 it does appear to be a little wet. Any suggestions?
