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    2010 Tuscany 20' need help with Fuel system

    Moved boat to a new lake 2 years ago and started having toruble with the engine stalling.
    Replaced fuel lines, water seperater, filter...and installed new 70HP yamaha motor.
    Still having same problems with stalling and not getting enough gas to engine... pump fuel bulb then will run again for awhile. Seems to happen more often in rough water... Thinking it's got to be a problem inside the Tank...maybe the fuel pickup./?
    The tank is built-in, and I'm hesitant to open... not knowing what to expect or look for inside once I remove the top valve and threaded nut... anyone been inside one of these sweetwater tanks, or have had a problem with the fuel pick-up./??
    any input would be great!


    • jetfixerjetfixer USAMember Posts: 45 ✭✭
      Sounds like you  could have a clogged vent system. Will the engine idle but then stall at high speed, or does it stall at idle also? Have you been using gas with ethanol in it? If so, your hoses may be soft and swollen or cracked. Softened hoses can collapse and squeeze off the flow of gas. Cracked hoses will allow air into the system and starve the engine of fuel.
    • gonfishingonfishin Member Posts: 6
      Thanks for the thoughts, Replaced all fuel lines and water separator this year. this weekend checked the anti syphon valve..seems ok, and opened the tank and removed the pickup and it looks fine, the screen was clean and and I was able to blow air through obvious problems, so put it back together took it out,  and...after 20 minutes of cruising in low speed to the marina for 10 gals of fresh (no ethanol gas) as the tank was getting low, then hit the speed lanes which got pretty choppy, gave it half power and within 1 minute it stalled out. Squeezed primer bulb and restarted, ran for 15 seconds then stalled again, while ski boats were fying by... repeted same pattern until we got out of the speed lanes and was able to idle back to docks. So intermittant, and only happens in choppy/rough water... I can rev it up at the dock and rock the boat back a forth a fair amount..but cant duplicate the problem...crazy! I'm at a loss what to do from here.. It's almost like there is a "tilt switch" on an old pinball machine!
      Thinking of buying an external tank...just to see if if resolves the problem...then I would know it's in the fuel system, right?
      Can you think of anything else that could cause this... possible electrical connection? This is a 5 yr old Sweetwater Tuscany, 20 ft, with a 2 yr old Yami 70, EFI engine.. ??
      Thanks for any ideas... have had problem for 2 years since moving it to this "unristricted" HP lake (Pleasant Hill) in Ohio.

    • jetfixerjetfixer USAMember Posts: 45 ✭✭
      At this point I would suspect the fuel pump on the engine. Or did you have this problem on previous engine? Also, check for good electrical connections at the engine, and also the battery. Rough water plus higher rpm's means more vibration. There is also the option of buying the Yamaha Diagnostic software and a test cable. I can plug my laptop into my engine and test everything, even while running on the lake. With a helper, you could monitor the fuel pressure and see whats going on when it quits.
    • gonfishingonfishin Member Posts: 6
      Great feedback.. We had a small 9.9 Yami from being on a restricted HP lake, moving to this lake 2 yrs ago and..started having problems. Needed a bigger engine anyway given this lake is unrestricted HP, and had the dealer check the tank... first spring day in the water last year it stalled half way to our docks with the spankin new engine...what a bummer. tried a few various things, but problem keeps popping back up.. the diagostic test sound like a good option to try before I pull it for the year. Thanks again for the input! 
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