Boat will not plane out, and rpms drop?

Question

Before I put it in the shop I have a question....

I have a 50hp Johnson 2 cyln... I clean the two carbs out and rebuilt them with new kits, Id just like to know if any one can help me out, I'm pretty good with motors but never messed with outboards soo this is it....

When hooked up to a hose It runs fine revs up in Forward Neutral and Reverse. When in water If I go to take off I give it gas and actually plane out for a second but as soon as it planes out the rpms drop back down to Idle speed, also a few times when turning and giving it gas it will rev to normal rpms, and Reverse it will work fine???? Dose any one know what may be the problem???

Answer 1

I don't know if this will help, but my 25hp Johnson was acting similar and it ended up being the primer pump on the fuel line.

Answer 2

Leave the trailer at the boat ramp : )

Answer 3

Fuel line problem or inline filter problem.  Replace the fuel hose and bulb as it may be losing the vaccum.

Answer 4

I think the guy before me might be on to something.  It sounds like you are loosing fuel.  It's either through the line like he said or something with the carbs, but you just rebuilt those.