Here is some background on how my 87 Johnson 90HP VRO has been behaving. No problem starting, idling, or low speed. I usually drive the boat about once a week for an hour or so. When i try to go on plane for the first time (W.O.T), i feel full power initially for a second or two then about 80% power. This will last the remainder of the time i am out. Previously (beginning of season)it would feel like it was cutting out on me (that exchange between 100% and 80% power). I would be at full throttle and you could hear the engine dip back and forth, then it would settle at about 80 percent power. It seems once the engine heats up, full power is gone. Here's what i have done to the boat so far. Compression check good, New fuel filters, water sep, plugs, carb kits and tune up. Could this be related to the spark plug wires? I did have a rare occurance a few weeks back where the boat ran like a champ the whole time. It had sat for two weeks and it was a cool day. The weird thing was, it seemed to have a worse idle, but ran W.O.T with no problem for over an hour. The next week, same thing... initial surge then 80%..HELP!!! Can't figure out if this is fuel or spark? Supposedly a spark test was done and it was good, but i'm not sure i believe in it.
