Lawn Mower backfire

Discussion in 'Mechanic and Repair' started by bluedude2288, May 22, 2004.

  1. bluedude2288

    bluedude2288 LawnSite Member
    Messages: 2

    I have a 4hp Brigs and straton and i am having a problem with backfiring. When i go to start it, it fires to soon causing it to whip the starting cord back in at high speeds, it almost broke my hand, what can be the prolem, all i can say is before i tried to start it, a couple of days before it got soked in water, some got in side, but i throughly made sure it was dry and replaced the oil to be safe everything was ok, what could be wrong with it back firng like this?
  2. Green Pastures

    Green Pastures LawnSite Silver Member
    Messages: 2,457


    Take out the spark plug and pull the rope a few times. Put the plug back in and try again.
  3. bluedude2288

    bluedude2288 LawnSite Member
    Messages: 2

    nope was tried, even checkd that i am indeed getting a spark, by holding it near the the metal and theres are sparks, it just seems to be firing too soon,
  4. fixer67

    fixer67 LawnSite Silver Member
    Messages: 2,098

    Your timing is off. You have a sheared flywheel key. DO NOT use a steel to to replace it with. If you use a steel key the next time it will be the crank that goes instead of the key.
  5. martinw

    martinw LawnSite Member
    Messages: 23

    I agree.... That is EXACATALLY how a broken flywheel fey acts.

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