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new Toro pt21 walk behind made a big "gunshot" noise

Discussion in 'Mechanic and Repair' started by wbread, Jul 3, 2008.

  1. wbread

    wbread LawnSite Member
    Messages: 4

    One of my workers was using the Toro 21 inch we've just got new this year, and after mowing disengaged the deadman bar, but engaged it again before it was completely shut down. This made a huge gunshot pop and it started weakly. The next few times it wouldnt start on the first pull anymore, and now it seems to be starting fine, but less powerful.
    I'm looking for any info on what could have made the pop, and if i need to service it, Thanks!
  2. jkason

    jkason LawnSite Senior Member
    Messages: 546

    When you let go of the deadman bar, the engine was still spinning and pulling through raw fuel without burning it. When you re-engaged, the spark turned back on, burning that fuel charge all at once - hence the "gunshot".

    We call it "Brown Shorts Syndrome".

    The reason it may not be starting, or starting with less power, is that when it "popped", it probably did so with enough force to partially shear the flywheel key. Pull the flywheel & check the key.
  3. wbread

    wbread LawnSite Member
    Messages: 4

    Thanks for the help. puts my mind at ease a bit. Seems to be working fine now though, aside from taking a couple pulls at the start of the day. Ill check that flywheel still

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