Backfire

Discussion in 'Starting a Lawn Care Business' started by onthesidelawncare, Aug 22, 2006.

  1. onthesidelawncare

    onthesidelawncare LawnSite Member
    from Jax. FL
    Posts: 43

    Today my Z started to backfire when I shut er down, what could be some of the reasons behind this?
     
  2. kmann

    kmann LawnSite Senior Member
    Posts: 298

    My JD 717a will do this if I shut it down without setting the brake, just as the owners's manual says it will.
     
  3. ChadsLawn

    ChadsLawn LawnSite Bronze Member
    Posts: 1,110

    hehe did it scare ya?

    leave the throttle anywhere from 3/4 to full throttle when shutting down. Its has to do with the fuel shut off in the pump.
     
  4. Charles

    Charles Moderator Staff Member
    Posts: 7,952

    My Lazer us to do this when it was newer. Now it rarely does. Didn't hurt anything.
     
  5. Post Mowing

    Post Mowing LawnSite Member
    Posts: 56

    Did you let it idle first?
     
  6. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,329

    Shut off the machine at full throttle and eliminate any chance of damage due to a backfire. Some people say that letting the machine idle will cool it off a little but I don't know about that on an air cooled engine. I haven't had any problem resulting from turning them off immediately at full throttle. But I am will to learn on the subject.
     
  7. CutInEdge Lawn Care

    CutInEdge Lawn Care LawnSite Senior Member
    Posts: 677

    You need to let machine idle down first. If machine is working at 1/2 to full throttle and you just shut it down 90% of time it will backfire. Good Luck!!
     
  8. Jnamo

    Jnamo LawnSite Member
    Posts: 90

    If it is air cooled and you let it idle a few minutes before shut off, it will still backfire. Try full throttle shut off.
     
  9. ChadsLawn

    ChadsLawn LawnSite Bronze Member
    Posts: 1,110

    Rob will tell him right. if its a Kohler you need to do what I said. Mine use to backfire all the time when I would let it idle then shut off. My old dealer told me to run it at 3/4 to full then shut off.
    But do what you want.
     
  10. lawnspecialties

    lawnspecialties LawnSite Silver Member
    Posts: 2,513

    This topic has been discussed quite often in the "repair" forums. If you don't like the 3/4 throttle technique, I used to let my Kohler idle at least 30 seconds (longer if I'd been working it extra hard), then turn it off. Never backfired when I did that. :)
     

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