I have a 1987 90 hp evenrude motor. I ran it around the lake for about 15 mins. and it ran great. Then with the throttle in the wide open position, the rpms went from 5500 to 3400. I was running a gas mixture from my other 88 hp motor so that i could check to see if the oil pump was working properly. the pump seems to be working ok as i marked it with tape and it had used some. The motor was also smoking alot at idle. i thought that the sparkplugs may have fouled so i changed them the next week. They looked ok but the top right cylinder plug appeared not to have much blackness at all on the electrode. I took the boat out again with the new plugs and it only ran 3400 rpm and seemed to be skipping. Does anyone have an idea where to start to trouble shoot this problem?
Thanks
Thanks