86 40hp Johnson 1/2 power with two people

[Gantz6]

motor has new tank lines and filter, carbs rebuilt, timing plate replaced, fins great to plane with one person, but add another and it won’t get past 1/2 throttle power just sounds like it’s working harder. Propeller has worked fine in past

 

[racerone]

Start with a compression test.------Or perhaps the boat is full of waterlogged foam ?------Seen that many times.

 

[Gantz6]

Compression is 115 in both, good spark,

 

[racerone]

Compression is not encouraging.----Test with another gauge perhaps.----Checked flywheel key ?