20hp Kohler Back firing after shutdown

Discussion in 'Mechanic and Repair' started by jlouki01, Apr 28, 2007.

  1. jlouki01

    jlouki01 LawnSite Senior Member
    Messages: 453

    I have an 05 Turf Tracer with a 20hp Kohler powerplant. I am starting to notice the tip of the pipe is getting black and the mower is back firing when I shut it off. Besides unusually bad gas mileage it runs fine. I can sometimes see a small thin cloud of black smoke when it's under heavy load.

    Any suggestions?

    Choke seems to be adjusted correctly..
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Are the plugs black and sooty ?

    It's possible there is a issue with the float needle valve in the carb. causing it not to close fully, Worn or trash.
  3. topsites

    topsites LawnSite Fanatic
    Messages: 21,653

    The following I would check:

    Air filter and pre-cleaner, also the pcv breather tube (there's no pcv valve but the rubber tube serves the same purpose). While you got the air cleaner off, check the choke valve and make sure it's fully open when at Wot.
    Fuel filter (might just replace it for gp) and while you got that off and the fuel shut down, carefully remove the bowl from the carb and kinda see if the float isn't stuck. Spark plug's been mentioned.
    Either with compressed air or some carb cleaner, clean thoroughly all the throttle linkage crap and springs and stuff.

    Beyond that, Kohlers need to idle a full minute after running Wot before you shut them off, so as to cool them down, yes all but the oldest ones backfire if you don't do this.
  4. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    Shut it down at full throttle.
  5. lawnspecialties

    lawnspecialties LawnSite Silver Member
    Messages: 2,524

    I've found both of these work. Kohler's are famous for backfiring.:)
  6. pugs

    pugs LawnSite Gold Member
    Messages: 3,025

    Yah, shut it down at half throttle or higher. Their anti backfire solenoid only operates on the main circuit of the carb...not the idle circuit.
  7. jlouki01

    jlouki01 LawnSite Senior Member
    Messages: 453

    Note taken on the throttle shutdown procedure. I have a few of these and only this ones pops when I shut it down. The plugs are black and sooty. Might drop it off at the dealer and have them work the carb over for me.
  8. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    Since your plugs are black have you checked to see if the choke is completely open?

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