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120 hp Force dies shortly after reaching high speed.

Posted By: HappyNest

120 hp Force dies shortly after reaching high speed. - 06/02/18 04:01 AM

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
Posted By: HappyNest

Re: 120 hp Force dies shortly after reaching high speed. - 06/02/18 04:03 AM

This is a 120hp Murcery Force 1999 model on a Nitro Sport.
Posted By: Taylored

Re: 120 hp Force dies shortly after reaching high speed. - 06/02/18 04:11 AM

Have you checked the pick up line in the tank?
Posted By: DREAMIN TEAM

Re: 120 hp Force dies shortly after reaching high speed. - 06/02/18 12:08 PM

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
Posted By: Droyhef

Re: 120 hp Force dies shortly after reaching high speed. - 06/02/18 06:34 PM

Take the cowling off and squeeze the bulb. Look and smell for leaks.
Posted By: HappyNest

Re: 120 hp Force dies shortly after reaching high speed. - 06/02/18 10:15 PM

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.
Posted By: HappyNest

Re: 120 hp Force dies shortly after reaching high speed. - 06/02/18 11:41 PM

Thank you all for the input You have given!!
Posted By: HappyNest

Re: 120 hp Force dies shortly after reaching high speed. - 06/07/18 08:22 PM

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.
Posted By: Droyhef

Re: 120 hp Force dies shortly after reaching high speed. - 06/09/18 10:10 AM

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.
Posted By: HappyNest

Re: 120 hp Force dies shortly after reaching high speed. - 06/09/18 01:04 PM

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!!!
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