This problem is driving me insane, I hope that one of the forum can help me diagnose and find the problem. I have a 1978 115 that's lacking power and will not idle correctly in the water. I got the motor running fine out of the water, I set the idle at about 1200 rpm, expecting the rpms to drop 3-400 once in the water. When I put the motor in the water, it will not idle. I have to rev it up a lot for it to stay running. I fiddled with the idle on the water until I could get it to start, idle, and shift into gear. My problem is when I take it out of the water and flush the motor starts and screams at around 2500-3000 rpm. The motor should not run like that. There is also a noticeable lack of power, it doesn't seem like it has 115hp. The motor runs good at all other rpm, wot, etc. It just will not idle properly for some reason.
Here's a list of the things I have done
Carb rebuild- The carbs are extremely clean, I bought the good rebuild kit with the little press in plugs that have to be replaced.
Timing check- Within specs at idle and at wot
Compression test- 110-120 psi on all cylinders, within spec.
Had 2 questionable ignition coils, they did not jump a 7/16" gap in open air. Replaced the coils.
New spark plugs Champion L77JC4 set at .040 and not .030 because the larger gap is supposed to help with idle issues. Its firing on all cylinders.
I always thought that it was going to be low compression on one or more cylinders so that once it was in the water there was too much back pressure causing these problems. However I was surprised at the compression numbers when I did checked it today.
I would really like some help on this guys. I'm the kind of person that likes things to work correctly and when it doesn't it drives me insane.
Here's a list of the things I have done
Carb rebuild- The carbs are extremely clean, I bought the good rebuild kit with the little press in plugs that have to be replaced.
Timing check- Within specs at idle and at wot
Compression test- 110-120 psi on all cylinders, within spec.
Had 2 questionable ignition coils, they did not jump a 7/16" gap in open air. Replaced the coils.
New spark plugs Champion L77JC4 set at .040 and not .030 because the larger gap is supposed to help with idle issues. Its firing on all cylinders.
I always thought that it was going to be low compression on one or more cylinders so that once it was in the water there was too much back pressure causing these problems. However I was surprised at the compression numbers when I did checked it today.
I would really like some help on this guys. I'm the kind of person that likes things to work correctly and when it doesn't it drives me insane.