15 horse Briggs eating spark plugs?

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Thread: 15 horse Briggs eating spark plugs?

  1. #1
    Join Date
    Jul 2021
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    15 horse Briggs eating spark plugs?

    I am pretty green with ohv engines so I thought it would best I asked you folks your opinion. My engine keeps killing spark plugs. They are not carbon fouled or oil fouled as far as I can see. They just stop working. I am at a loss as to why it?s happening. If I pull the plug wire and wedge it 1/8 inch off the top of the plug, it starts up and runs fine. If I connect it to the plug then it won?t run.

    It has:

    New plugs
    New coil
    New ignition
    New carburetor
    Fresh gas
    Charged batter

    Has anyone ever experienced this? What could it be???

  2. #2
    Join Date
    Dec 2018
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    Muskoka, Ontario
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    89
    I would check the high tension wires for continuity/bad connections/messed up heads where they connect to the spark plugs themselves. Sounds like when you wedge them around you force them to make a connection but when they are resting where they should be the connection is lost

  3. #3
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    Thank you, I will check that.
    It was doing it before I converted it over to electronic ignition. And seems like it?s still the same problem but I swapped the coil and plug at the same time so I can?t confirm that the original plug had gone bad. I think already threw it away so I can?t put it back in. When it stops running and I replace the spark plug, it starts and runs like it should.

  4. #4
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    What engine model do you have?


    My new beer holder spilled some on the trails - in it's hair and down it's throat.
    Joe Camel never does that.

    Advice is free, it's the application that costs.

  5. #5
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    Jim:
    It?s a single cylinder 15 or 16 horse Briggs. It?s the old style with an up draft carburetor. Other than that, I?m not sure of a model number. It was painted before I got it.

  6. #6
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    Mississippi
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    So what is the time interval between fails? Does it run only a few minutes before failure or days? Hypothetically if your engine mounts were bad and torque is causing your engine to move around a bit, is there anything the plug can come into contact with and perhaps break the insulation?

  7. #7
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    At first I was going to suggest the diode wire, but seeing as it is a single, and you are breaking the ground when you disconnect the plug wire.
    I am going to guess it could be either your magneto kill wire shorting either in line or inside shroud, or key switch either bad or searching for ground.
    Being as the problem was the same before and after new coil it probably is not that.

    I might try disconnecting the kill wire at the coil and go for a ride, if it doesn't shut down that's it. You will have to starve the engine of air to shut it down.


    My new beer holder spilled some on the trails - in it's hair and down it's throat.
    Joe Camel never does that.

    Advice is free, it's the application that costs.

  8. #8
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    Dirtdobber:
    I?m on the 3rd plug. The first one was the original that came on the engine. I got maybe 6 hours out of it before it stopped working. I bought the exact replacement and it ran for about 2 hours before it essentially burned out. I?m wondering if it?s the wrong plug but the right dimensions? Maybe the electrode in the center is melting internally? Can a plug be disassembled without destroying it, to see if anything is wrong with it? I?ve never tried to take one apart without the use of a hammer ha ha.
    The engine mounts are solid and it doesn?t move for the plug to make contact with anything.

    Jim:
    I will try that, thank you!

  9. #9
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    Feb 2013
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    shenendoah valley,va.
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    i read where one small engine mechanic said burning up plugs is usually caused by '' pre-ignition '' . not sure how that's fixed ..but it may be something to check . jboy va.

  10. #10
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    I'm curious, does this engine have a low oil shutdown system on it? If so, check level, bypass it and see if it still happens.
    Also, have you tried putting any of the old plugs in? Champions used to have a bad reputation of doing this years ago and some were bad out of the box.


    My new beer holder spilled some on the trails - in it's hair and down it's throat.
    Joe Camel never does that.

    Advice is free, it's the application that costs.

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