Engine runs great on muffs, stalls in the water

[Rleemorris]

2000 Chris Craft with a Volvo Penta 5.7 GSI, only 255 hours, engine block new in 2009. We started with the typical power loss while on plane one day that I've seen posted by VP owners over and over again. New gas, new fuel pump, spark plugs, wires, ignition coil, distributor rotor and cap, various sensors, including the MAP. The boat now runs great on muffs in driveway. However, the minute it touches water, it will idle, but won't run in gear. My husband took apart one of the risers last night. We don't appear to have any of the infamous Volvo Penta flaps that have caused so many issues, although we do have some corrosion. I should say this boat has spent all of these hours in the Coastal Carolina area, tidal rivers, and salt water.
Any suggestions?

 

[jtybt15]

Need more info. Do you mean the boat won't shift into gear? Does it shift while on muffs?

 

[cwms]

Ok, you replaced lots of stuff. Did you check/replace the fuel filter

 

[Cam]

Sounds like a fuel delivery problem. Try running on a seperate tank (gas can) and see if that solves the problem. Could be something blocking the tank pickup or a hose collapsing when throttling up. Boat sits at a different angle when sitting in water as opposed to sitting o trailer or blocked up.

 

[GeeBee]

Shot gunning is not going to fix it. It is a 2000, so it has a MEFI. Did you run a code check to see if there are any faults?