I have a 1988 Yamaha 40 hp 3 cylinder. When we put it in the water last weekend (after sitting for 4 months) it idled a little rough. This was more noticable when put in gear and a load was on the engine. It ran pretty good wide open. The next day it still idled rough and would not open up and run at high speed. It will rev in neutral though. I pulled number one plug wire off and it didn't make much difference in the way it idled. When I pulled number two wire it dropped in idle. When number three was pulled it died. So it appears number three was doing most of of the work, number two just a little and number one hardly anything. Why would it run worse the second day? I spoke to a Yammy mechanic and he said it sounded like a fuel problem. I thought it sounded like ignition the way it will cut in and act like it will run then cut out again. But there is spark to all three cylinders. Do I have an ignition or carb problem? The Mechanic suggested rebuilding the carbs but I hate to start there if it's not a carb problem.
