Help! Why does my PWC run perfectly on the trailer but won't run once in the water?

[jogifford]

Once in the water, my 2001 Polaris Virage will idle but not accelerate. Tring to accelerate will cause it to bog-down, die and/or overheat...

 

[sjbs]

Have you looked under your pwc when it is on the trailer.I picked up a plastic bag on my Wetbike that wrapped around the impeller shaft.It would run on the trailer but it could not run much over idle once in the water.

 

[jogifford]

I hoped you were correct and took apart the propulsion system/impeller -- nothing appeared to be wrong. Think I'll just donate this PWC to BoatAngel.com or something...

 

[sixfigures]

On the trailer there is no load on the engine and no back pressure on the exhaust, first do a compression check and check for fuel to all cylinders and for spark to all cylinders. Spark plug color will tell you a lot about the engine also. SILVER, GREY, WHITE, BROWN, BLACK all mean something different is going on inside the combustion chamber.
Most weak or messed up engines sound good out of the water. On the pump issue also check for clearance between the edge of the impeller and the liner excess wear will cause serious cavitation.