Need an idea on what may be wrong. The boat starts and ideas fine. On plane it will run at 50% throttle. At full throttle it runs a short time and dies. We watched the fuel filter during this process and the fuel is removed from the filter at high speed. You can pump the prime bulb and return fuel to the engine and it will continue to run at low speeds.

Cleaned The carburetors (Lower carb had stuck needle valve)
Replaced filter and hoses to carburetors
Replaced fuel lines from the tank
Replaced bulb

This is a 120hp Murcery Force 1999 model on a Nitro Sport.

Have you checked the pick up line in the tank?

You may want to check the fual pump . Sounds like low capacity . If you can squeez bulb and continues to run high speed that would be an indicator

Take the cowling off and squeeze the bulb. Look and smell for leaks.

I have not checked the pick-Up tube yet only because it is difficult to access. I did order a fuel pump kit and will install that next weekend. Iwe took the cowling off and pumped the bulb and the only place gas came from was the carburetor air intake. I had it out today and now you have too pump the build alit to pressurize the system before starting. I am starting to think I�ll need a pickup tube.

Thank you all for the input You have given!!

Okay so I rebuilt the fuel pump and while the rubber was about ready for replacement, it didn�t have anything apparently wrong with it. I pulled the fuel pickup and it has a small screen in it that had a ball of lint like material that had it largely restricted. No cracks in the tube so I cleaned it and returned it to service.

If fuel came out of your carb air intake while you pumped the bulb you have a needle stuck open. May not be your issue but it shouldn't let fuel by once you have pumped the bulb up and filled the bowls.

I am glad you said that Dawson, while cleaning lower carburetor I did find a sticking needle valve. I just didn�t connect that point. Seems obvious now that you mention it. Thank you!!!