No power in the water!

[MARIUS1967]

I have a 55 AE 663 Yamaha motor on a 4.2m rubberduck.The motor is revving up nicely when tested outside the water, the impellors are working great. As soon as i put the boat in the water and try to get it to speed, there is no power and the boat does not plain out of the water. If i put it in neutral the revs are great but once into gear and on full throttle there is no power. What can the problem be?

[99yam40]

motor needs more fuel to create power under load.
Check compression, spark, and timing
If all is good then look at carbs,
most problems are fuel related, but have to make sure motor is in good health