Problem with Stihl fs85r trimmer

Discussion in 'Lawn Mowing' started by The mayor, Jun 4, 2006.

  1. The mayor

    The mayor LawnSite Senior Member
    Messages: 592

    I am having a problem with my trimmer, the crank case fills up with gas when it sits over night. I can run it, then shut it off, place it on the garage floor. When I come out the next day there will be gas on the floor and I won't be able to pull over the motor because of how much gas is in the engine. Anybody have this problem and came up with a fix. tia
  2. lawnmaniac883

    lawnmaniac883 LawnSite Silver Member
    Messages: 2,613

    Open up your carburator and clean it. Pay special attention to the needle valve. Remove and inspect needle and replace if necessary.
  3. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,354

    As the previous post says gas is getting past the needle valve somehow. I have seen this on Echo230 and fortunately it comes and goes, mostly goes. Sometime I have seen pressure build up in the tank when that happens and I don't see why that would happen but I also don't see how the pressure would be relieved Echo has a breather but that don't let fuel out and neither do caps.
  4. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087

    Yep, needle valve.

    My 85 did that once... filled up top side and it would not turn over period, wouldn't even budge. I was afraid and puzzled. I thought at first it might have siezed right after I shut it off from a long hard run. But I had ran into this on a mower engine before and that popped in my mind a second later.

    Anyways, just pick up a rebuild kit, new air filter, new fuel filter, new fuel delivery lines and a new primer bulb. Grab the gasket set too. It's all cheap and you may as well replace it all if you have to take it off for cleaning. Then everything is new.

    In my case, I never was able to fully correct everything by rebuilding, but most times you can, and you should just spend a few bucks to do it while you are at cleaning it.

    Personally, if I had it all to do over, I would have just pulled it all and installed NEW including the carb. My TIME was worth more than all the tinkering I did, much less the hassle. Once I popped the new carb on in a couple minutes, I had a new trimmer again.
  5. The mayor

    The mayor LawnSite Senior Member
    Messages: 592

    Thanks for all the advice. I will do a cleaning of the carb first...then go from there. This site is just great for honest help. thanks again.

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