250 yam shut downs at higher rpm

This is a 2001 turz efi 2stroke ,but the powerhead is 2004 with 78 hrs on it as of now. This engine sits from April 1 to Nov.1 with a full tank of gas(I'm told it cuts down on condensation in main tank with stabil conditioner).new water/separator, The fuel was drained halfway and replaced with fresh gas for the first trip out,and 15 miles out engine at 4000 rpm quit,restarted and went a mile further with no problem with higher rpm ,went home at 4300 rpm and no problem,next two trips no problem.Yesterday 25 miles out ,running great at 4200rpm ,engine quits with no stuttering,but restarts instantly. Changed water/separator in boat and dumped under engine cover filter with floating red ring that was up as high as it would go while on the water and the engine still cut out after one minute of high rpm .No warning horns but did notice slight speed reduction prior to shut down. Came back at 3000 rpm and not a cut off,run smooth but not on plane,last mile of trip ran 2 miles at 4200 on a 12 gallon of new gas and no problems. Cleaned main tank out and did have some water. any ideas appreciated .Can the shut-downs ruin the engine?

Re: 250 yam shut downs at higher rpm

More info.Took a drive down the coast to a yammy dealer in homosassa fl and the man is a 5 star rated mechanic ,and when i gave him the run down he came back instantly with a bad "main system relay" of which he had only a few go out,and the "Winkey Blinky" won't pick it up.So I'm asking with that relay snug against the block in the junction box does the heat from the engine affect the relay? I'm in the process of changing all three low pressure pumps although I'm getting a reading of 35 lbs pressure at the vst schader valve.Vst tank was clear and so was the filter at bottom of vst motor.I bought the 200 dollar relay and is in place so any other ideas will be appreciated.

Re: 250 yam shut downs at higher rpm

the bad relay ,which I doubt, wont get picked up because the system looks at it as a shut off at the key. the 35 psi reading just means the high pressure pump is working not that its pumping gasoline. at high speeds the low pressure pumps feed the VST where the high pressure pump gets a VAPOR free supply of fuel.<br /> I have not seen a V6 relay fail yet but some of the F115 relays have.<br /> that red ring will only float if there is water in the filter it does not float in gas.<br /> most likly you filled the VST with water. EFI does not act up like carbs and fuel supply problems can and will create an instant shut off. if you dont belive me squeeze the high pressure line, at 4500 going across the water, with a pair of pliers and see how instantaneously it quits.<br />if the main relay drops, all engine electrical functions including the fuel pump quit. but failure is rare.

Re: 250 yam shut downs at higher rpm

Thanks rodbolt, and after reading your answer it probably was the water .But anyway I had the boat out yesterday for several hours and the 250 hummed like a spinning top and no problems. I love my mammy and my yammy.