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Stihl KM 90 leaking fuel into air filter

Discussion in 'Mechanic and Repair' started by 4slservices, May 2, 2013.

  1. 4slservices

    4slservices LawnSite Member
    Messages: 46

    I have 3 Stihl KM 90s. They are the same engine as the FS 90 trimmer. This problem has happened to the 2 older ones. Gas leaks into the air filter when not in use, no matter which way trimmer is positioned. I ordered a new carb and its still happening. Could it be the gas tank vent? Is there a way to clean them or do I just have to buy a new one. Anyone have this happen to them. Its starts and runs just fine without a gas soaked air filter on it.
  2. ricky86

    ricky86 LawnSite Bronze Member
    Messages: 1,887

    If you're sure it's not the carb, then yes it's the vent. You might see it leak. Turn it upside down and watch the little port in the a/f base.

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