Boat won't plane, but runs great no load

[peekayphx]

1985 Ranger 18" bass / ski. 150HP Mercury OB. Bought the boat used. Starts and runs well. When applying throttle wont plane. Tried many different trim levels. Tried adding choke. Still dies about half way through throttle unless you back it right off. Runs fine up to half throttle. Took it to my boat shop and they put it on DYno and ran it for hours at all RPM and it runs fine. They cannot recreate the problem out of the water. Could it have the wrong prop on it from previous owner, as it has done this since I bought it? If so, how do I find what original equipment prop was for this boat?

Thanks
Cindy

 

[ScottyJGA]

Re: Boat won't plane, but runs great no load

When they run an engine on a dyno it sits still. When you throttle it up on your boat, it tilts back as the boat's bow rises. Maybe there's a carb float issue or something else that happens only when the engine tilts?

 

[peekayphx]

Re: Boat won't plane, but runs great no load

Carb rebuilt and fuels tanks drained and cleaned checking for debris and water. New fuel lines run and new primer bulb installed. New fuel water seperator installed. Shop has been very helpful but they are at a loss. They will take it to the lake, but at hourly rate. I haven't O.K.ed that yet.

I also run a big load on it. 4 People, 3 batts, days worth of junk on board. But I have tried it with just me and no stuff on board Same result.

 

[j_martin]

Re: Boat won't plane, but runs great no load

Weigh the boat and trailer. I will bet you're carrying 1,000 lbs of water in the floor foam.

or else you're waaaayyyyy overpropped, like a 28 or 30 inch pitch.

hope it helps
John