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12 HP B&S will not fire


tej

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I have a 12 HP Briggs that will not fire. I have pulled it off my B-112 to check the Magneto. As of now I have replaced the magneto, the points, the condenser, and the spark plug. The flywheel has not shifted on the crankshaft. I still get no spark and can not understand that when all the ignition parts are good. Anyone have an idea what could be keeping it from firing?
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I can only repeat what happened to me. I did the same things you did, but didn't tighten the locking nut after I set the points. Also the wire that goes from the points to the ignition switch could be grounded. Also if you don't turn it fast enough it won't spark.
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Sounds like you have a short somewhere. CLean your points, just take a dollar bill and drag it between the contacts on the points (closed) a few times. Works like a charm. ddh
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The engine is off the tractor so there is no short or ground. Points have been cleaned and checked with a meter. Condenser is off a working engine. Putting a rope around the starter pulley should spin it fast enough to fire, this will fire my other 12 HP briggs, but tomorrow I will put the starter on and spin it with that and see if that makes a difference.
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Well one side of the points are grounded when they are screwed onto the engine block. The other side is grounded when the points close. That’s what collapses the magnetic field in the primary winding to generate the spark voltage in the secondary winding.
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If you have it fully wired, make sure there is not a problem with the wire going to the ignition switch. This is grounded when the ignition is off and open with the ignition on. I would unhook that wire from the switch and try it.
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