Stihl BG85 won't stay running

Discussion in 'Lawn Mowing' started by Ford850, Jun 18, 2009.

  1. Ford850

    Ford850 LawnSite Member
    Messages: 132

    I have a 3 year old BG85 (very light use) that has always started and has run fine. This week, I cannot get it to run. It starts after the normal few primer pumps and then turning the choke off, like normal. But then it sputters for 3 seconds then dies. If I pump the primer bulb once every 3 seconds it continues to rough idle. As soon as I stop it dies. I dumped the tank, and refilled with fresh 89oct mix. No luck. Checked the L and H settings, and the LA, but nothing changes. Air filter is clean. I pulled the fuel line from the carb and I can blow through it easily. I pulled the filter off the tank end and pinched it closed and blew into the other end, and could not detect any leaks.
    Other than dropping it off at the dealer, does anyone have an idea of what might be wrong?
  2. Two Seasons

    Two Seasons LawnSite Senior Member
    Messages: 791

    Plugged screen in the muffler?
  3. Roger

    Roger LawnSite Fanatic
    Messages: 5,940

    With very light use over three years, perhaps the carb is partially clogged. I will assume it sat idle for much of that time with fuel in the tank and carb. Good assumption? Lack of use is usually more detrimental than too much use.

    I have a BG85, and it fires first or second pull. But, I use it many times each day, and it gets very heavy use in the Fall for leaf cleanup.
  4. topsites

    topsites LawnSite Fanatic
    Messages: 21,653

  5. SimonCX

    SimonCX LawnSite Senior Member
    Messages: 731

    Check the spark arrest first if it's not that take apart and clean the carb and clean the exhaust port. That usually does the trick.
  6. integrityman

    integrityman LawnSite Bronze Member
    Messages: 1,713

    I too would check- inspect the spark plug brush and regap it. The carb could be fouled, and you may have a tiny piece of dirt stuck in one of the needle valves.

    It may be worth your time just to drop it off and have it looked at/ fixed.
  7. Ford850

    Ford850 LawnSite Member
    Messages: 132

    I'll take a look at the screen and carb again. I had the carb off and should have looked closer at it. I've cleaned and rebuilt larger carbs before, but never one from a small engine like this. Do you remove and soak them? Spray a cleaner into the air intake while installed? I have carb cleaners and Seafoam, so what's the best way to clean this little thing? Thanks for your help.
  8. SimonCX

    SimonCX LawnSite Senior Member
    Messages: 731

    I usually take them apart and blow them out and only use spray cleaner if needed. If you did larger carbs then you won't have a problem.

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