85HP Johnson Poor WOT Performance

[georgeboat]

1976 on 16ft Glastron. Runs great at first- more than 5k rpm and goes 38-40 mph. Everytime I stop and cut engine then restart it runs very poorly at WOT- will not hit 5k rpm and will go about 35 mph tops. This happens everytime after the first stop (engine cut). Have worked on it and had it in shops- can't get it solved. Here is the list of what has been tried:

Carb rebuilds- a few times;
New Stator, coil pack, all coils, spark plugs, thermostat, water pump. Compression is good.

Starts like a champ and runs great but at WOT. As a side note, this began years ago after I lost a prop fin and limped back to ramp.

 

[emdsapmgr]

Re: 85HP Johnson Poor WOT Performance

Take an inductive timing light with you the next time you go out. When the engine starts to act up, put the light on each of the 4 plug wires and check for misifires and no fires. You did not mention replacement of two other ignition components, the power pack or the timer base. Both are expensive and can be the problem. Some investigation is worthwhile, considering their cost. If the spark checks out ok, then it's a fuel issue.