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Fuel solenoid problem?

Discussion in 'Mechanic and Repair' started by rccpjtindall, Jul 16, 2008.

  1. rccpjtindall

    rccpjtindall LawnSite Member
    Messages: 10

    Hi guys,
    I recently purchased a short block for my 16 hp briggs on my snapper z-rider. Put it back togethor with the old head and now it wont run. Gas sprays from the exhaust and back threw carb, when it does hit it backfires threw carb. could this be caused by the solenoid, I didn't change anything on the head and it ran fine before the block cracked. Any help would be great.
  2. Phil G

    Phil G LawnSite Senior Member
    Messages: 843

    Hi, I figure if gas is spitting out the exhaust then the fuel is getting through, the the solidiod is working. If it's back-firing then I'd look at the valves gaps, seems like the inlet might be a bit tight.
    Could be ignition. Did it have the ally fly wheel key? If the flywheel is not tightened to the correct torque then it can shear the fly wheel key on the first crank.
    Check these first as they are the first line of attack.

    Just seen is this a single cylinder side valve? If so then the valves were instaled by the factory, but still check gaps.

    Good luck Phil:usflag:
  3. rccpjtindall

    rccpjtindall LawnSite Member
    Messages: 10

    I checked ignition first thing, I'm getting good fire and the motor will hit and back fire out the carb. A guy asked me to smell the oil to check for gas --its strong. I didn't have much gas in the tank, but what was in the tank is now in the crank case.
  4. rccpjtindall

    rccpjtindall LawnSite Member
    Messages: 10

    As for the valve, all I did was take the head off and put it back on. Would I need to readjust the valves for the new block?
  5. Fisher40037

    Fisher40037 LawnSite Member
    Messages: 36

    Remove the flywheel nut and look at the sheared key, and listen to Phil from now on......

  6. rccpjtindall

    rccpjtindall LawnSite Member
    Messages: 10

    i'll check key as soon as I get back from work, But if the key was sheared would the motor be turning over or would the flywheel spin on its shaft?
  7. Phil G

    Phil G LawnSite Senior Member
    Messages: 843

    When a flywheel shears it just staggers a small amount. The timing will be out.
    Been thing; is the air gap on the flywheel/coil set right. This can spark when earthed but not under compression.
    Rotate the flywheel so the magnets are away from the coil and place a piece of card between the flywheel and both coil pick-ups. Rotate the flywheel so the magnets on it are in line with the coil. Loosen the coil and let the magnets pull the coil to the flywheel, squashing the card. Tighten up the two bolts on the coil and slowly rotate the flywheel to remove the card.
    Use a piece of card the thickness of the type you get spark plugs in.

    Good luck Phil:)
  8. rccpjtindall

    rccpjtindall LawnSite Member
    Messages: 10

    Hey guys,
    just checked the flywheel and the key is fine. I didn't have time to readjust the coil yet, but it looks pretty close. will hopefully get off work a little earlier tomorrow to spend some "quality time" with the mower.
  9. Phil G

    Phil G LawnSite Senior Member
    Messages: 843

    This is proving to be an awkward little sod. If the ignition seems ok and you can witness fuel in the system I'd just take two minuets to check the valve gap.
    Most manufacturers get it right all the time, but once in a while one gets through. I remember many years ago I fitted a Wisconsin short block and found it would not start because the valve timing was out from the factory.
    When you're trying to fire this up for the first time leave the air filter element out just to help it breath a little easier.

    Good luck Phil :usflag:
  10. sawman65

    sawman65 LawnSite Senior Member
    Messages: 751

    give me the model# cant help with out it.

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