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Stihl FS110 4mix Cutting out High RPM'S

Discussion in 'Mechanic and Repair' started by sealcoatnow, Aug 25, 2009.

  1. sealcoatnow

    sealcoatnow LawnSite Member
    Male, from Virginia
    Posts: 97

    Can anyone give me some advice on this?
    I have a FS110 with 25-2 trimmer head. It runs excellent and starts easily until under a load at high RPM's. It will rev fine until I attack really tall grass. it almost seems like an electrical problem as it cuts right off. I can keep it running if I close the throttle-it goes to idle. Running clean fresh gas, filter looks good and unit is about 2 years old. Never had the Spark Arrestor out but not sure if this would do it. Any help is appreciated.
  2. topsites

    topsites LawnSite Fanatic
    Posts: 21,653

    Coil or carburetor, sorry I'm not sure which one right now and I'm also assuming
    a lot of stuff, like you already put a new air filter and a new spark plug in it.
  3. 1998tahoe

    1998tahoe LawnSite Member
    Posts: 233

    Sounds like carb needs adjusting. Sounds like maybe going lean. My fs90 don same thing back in spring, service guy adjusted carb and ready to go.
  4. Two Seasons

    Two Seasons LawnSite Senior Member
    Posts: 791

    Sounds like a combo problem.
    1.) Take the screen out and clean it with gas.
    2.) Mix up a new batch of 92 octane with Stihl HP Ultra oil
    3.) Check the valve gap for 0.015"---if you can't do it, dealer will for about $40.
  5. mowerknower

    mowerknower LawnSite Senior Member
    Posts: 766

    Not likely the coil, usually if those coils fail they will start up but not accelerate at all. Most likely a fuel delivery issue. Just out of curiousity have you replaced the plug yet. not saying it could be the problem but I did have an issue with this before

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