Walker backfire

Discussion in 'Lawn Mowing' started by nlminc, Feb 21, 2000.

  1. nlminc

    nlminc LawnSite Bronze Member
    from GA
    Posts: 1,671

    Do any of you Walker owners get a backfire everytime you shut it down? I even let mine cool down a bit first. My dealer says that it is normal.<p>Sometimes I even see the face of Mr. Stone in that little burst of flames! :)
     
  2. OBRYANMAINT

    OBRYANMAINT LawnSite Senior Member
    Posts: 555

    MY DEALER TOLD ME TO LEAVE IT AT FULL THROTTLE TO ALLEVIATE THIS PROBLEM AND IT WORKS GOOD FOR ME(AS YOU TURN IT OFF)<br>ALSO MINE SOMETIMES BACKFIRES WHEN IT GETS REAL BUMPY , THE FUEL PUMP CAN BE CHANGED TO MECHANICAL FROM THE VACUME TYPE THAT MANY HAVE<br>DOUG<br>
     
  3. Evan528

    Evan528 LawnSite Silver Member
    Posts: 2,144

    my dealer told me to let the mower run for a minute on slow throttle to stop the back fire...unless i do that for about a minute theres always on backfire. it is so loud sometimes that costomers have ran out of there house to see what blew up!
     
  4. McLawn

    McLawn LawnSite Member
    Posts: 8

    It has to be a Kohler, they are famous for that. We were told to shut off at half throttle. This helps alot. You will have to experiment with the throttle setting that works best. <p>----------<br>Brian<br>McLawn<br>
     
  5. nlminc

    nlminc LawnSite Bronze Member
    from GA
    Posts: 1,671

    Thanks for the info. I will try the trottle at hafe and full to see if I can stop this. That backfire is killer especially when it happens in my enclosed trailer. It's not the way I want to be noticed in a neighborhood.
     
  6. Retro67

    Retro67 Banned
    Posts: 207

    My 15 hp Kohler Command Pro does the same thing.It has since it was new. Scares the daylights out of you if you don't expect it. Maybe will try shuttting down at medium throttle speed. Shutting off at low nor high speed neither seem to fix the problem.<br>&lt;p&gt;Does anyone know the technical aspects as to why these engines backfire like this? I'm not too keen on engine knowledge.&lt;p&gt;John
     
  7. HOMER

    HOMER LawnSite Gold Member
    Posts: 3,183

    As I understand it, there is leftover gas in the combustion chamber. By idleing the mower down all the way and letting it run for a minute or so it is supposed to burn off the excess. I never shut mine down at full throttle!! I used to until I was told that then I tell everybody that gets on them to idle it down first, problem went away!<p>Homer
     
  8. Charles

    Charles Moderator Staff Member
    Posts: 7,850

    I was wondering if I was they only one who has this problem. Whew!!!! My command has been doing this since I bought it also. I always down throttle it all the way. Still does it almost everytime. Mechanics told me this was normal. Glad to find out for sure now.
     
  9. This happens with these cheap one lung engines that have an automatic compression<br>release. When the engine spins at the low<br>speed as one would when they are pulling the recoil starter the engine ignition timing is<br>automatically ********.<p>So when the engine is shutting down the compression release is activated. Even though<br>there is no spark the heat of compression still fires the charge while the exhaust valve is open slightly.
     
  10. JJ Lawn

    JJ Lawn LawnSite Senior Member
    Posts: 350

    On the Walker if you have the 20hp or 25hp, if you ever notice in the evening that the muffler somtimes has a red glow to it after running it for a while? Well, when you shut down the engine the fuel pump is still pumping gas which is not being fired by the sparkplug because electrical system is off. This gas then goes into the muffler where it does what gas does when exposed to high heat. It explodes. So if you let your engine idle for a little bit before you shut down this can lesson the explosion. <p>jim
     

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