2003 lazer hp back fires

Discussion in 'Lawn Mowing' started by PRO PROPERTY CARE, Aug 5, 2003.

  1. PRO PROPERTY CARE

    PRO PROPERTY CARE LawnSite Member
    Posts: 198

    does anyone else have prolems with there machine
    back fireing. Mine does every time. the only fix is to let it idle for 4 or 5 min then it shuts off quietly.
    thanks for the help
    dealer is trying to get a response from exmark about it.
     
  2. Frank2

    Frank2 LawnSite Member
    Posts: 102

    When my dealer sold me my lazer he advised me that this would happen if i did not let idle for a few minutes. Of course he was right. Easier said then done....as soon as i'm done mowing, I start up the trimmer and I'll be on the other side of the lawn after a couple of minutes...I'm not going all the way back to the trailer to turn it off. Just not practical to do when were on a tight schedule.
     
  3. imograss

    imograss LawnSite Senior Member
    Posts: 796

    i always let my mowers idle at the lowest speed for a few minutes, that solves the backfiring.
     
  4. PRO PROPERTY CARE

    PRO PROPERTY CARE LawnSite Member
    Posts: 198

    ok, but the new mowers dont back fire
    I used there brand new lazer hp last week while they serviced mine and I couldnt ;get that sucker to back fire no matter what i did.
    did exmark change something this year.
     
  5. Jman

    Jman LawnSite Member
    Posts: 217

    What engine do you have? If it's a Kohler leave the throttle wide open. Do not idle it down.
     
  6. lawn perfection

    lawn perfection LawnSite Senior Member
    Posts: 347

    WHAT JMAN SAID, SHUT DOWN AT 1/2 TO 3/4
     
  7. Rick Jones

    Rick Jones LawnSite Senior Member
    from NY
    Posts: 427

    Why shouldn't he idle it down if it solves the problem?
     
  8. 65hoss

    65hoss LawnSite Fanatic
    Posts: 6,360

    Its pretty normal. You didn't say what motor you have. All my kawis have been bad about that when new. As they got some hours on them they got much better.

    There is a couple of threads in the eXmark forum about the backfiring. What I do on my HP is always shut the fuel off and let it run out. No backfiring this way at all. It also allows the motor to cool off.
     
  9. Jman

    Jman LawnSite Member
    Posts: 217

    Rick,
    You asked why not idle it down, good question. My response is what cools this engine???? Isn't it an air cooled engine? Where does the air come from? It's the fan. When you slow the engine down do you increase or decrease the airflow from the fan? The only thing that cools down at idle is the muffler. That is were the backfire occurs. That is harmful to the muffler. It does less damage than dieseling when you shut the engine off hot internally and the fuel in the engine ignites due to heat. It's a catch 22. The engine manufacturers now have solenoids on the carb to shut the fuel flow off thru the carb itself. It shuts off the high speed jet only, not the idle jet. When you bring the engine down to idle and shut it off you will still pull fuel thru the idle circuit and it will deposit in the muffler causing the backfire. When you shut it off wide open. No fuel flows thru the high speed jet, no bang.
     

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