Engine won't move the boat at usual speed during full throttle

[[email protected]]

I have a 1992 Evinrude 115hp outboard. We took it out to waterski and did just fine. Boat pulled skier at about 25mph. Later we stopped and went fishing. On the way back the boat would only go about 9mph at full throttle. We tried several things to include priming the gas bulb and marked the propeller to see if it is a spun hub but nothing seems to show as a problem. We took it out today and have the same issue. Likely going to replace the fuel filter tonight. Any suggestions on what may be the cause of this?

 

[flyingscott]

You need to do a compression and spark test.

 

[[email protected]]

You need to do a compression and spark test.

Thanks I will give that a try and see what happens.

 

[Boobie]

Do a cylinder drop test on it also. That may tell you something.

 

[[email protected]]

Thanks I will give that a try and see what happens.

Compression test went well. Tried the spark test but the meter I purchased did not seem to work. I decided to take it to a mechanic for further evaluation.

Thanks for trying to help me.

 

[bobbyc]

A simple test would be to to use your hand to compare the temperature of each cylinder head shortly after the motor is shut down. If all cylinders are contributing, their temperature should be roughly the same.