I have a 1989 Ebbtide with a 5.7 liter Mercruiser and Alpha One outdrive. Starting this season, when we launch the boat and run for 20 minutes or so, it runs like new (4400 rpms & 54 mph). After running, we stop and anchor for 1 to 1 1/2 hours. Restarts fine and when we throttle up to wide open the boat will start to miss. Max rpms less than 4000. Throttle down to roughly 2000 rpms and misfire goes away.
Have changed plugs, wires, rotor, cap and sensor in distributor. Cylinder compressions from 145 to 155. Fuel pressure from 4 - 7. Carburetor rebuilt a few years ago.
I am convinced it is heat related, as when anchored, the heat builds up in the engine compartment. Again, it runs fine/normal when first started up and run. I'm thinking electrical/ignition.
Thoughts/suggestions?
Have changed plugs, wires, rotor, cap and sensor in distributor. Cylinder compressions from 145 to 155. Fuel pressure from 4 - 7. Carburetor rebuilt a few years ago.
I am convinced it is heat related, as when anchored, the heat builds up in the engine compartment. Again, it runs fine/normal when first started up and run. I'm thinking electrical/ignition.
Thoughts/suggestions?