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What did I fry?


knopow

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Ok, so I was changing the spark plug in my 3212H and made the bonehead mistake of slipping off the plug and connecting the positive on the starter solenoid to the top of the spark plug. The socket wrench promptly welded itself in place and it sat there for a few seconds while I ran and got a hammer to knock it off. Now I can get it to crank, but no spark. What would you suggest as a course of troubleshooting? Of course I can start replacing points and condensors, but I was just wondering if anyone had a diagnostic approach vs. maybe trial and error. Thanks Much, Jeremy
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Jeremy, I would take the spark plug out and inspect it just for the heck of it, and see if anything can be learned from it. Then I'd put in a new plug just to save the trouble of it. Then, I'd try again and troubleshoot. If a new spark plug doesn't do the job, you can put a jumper cable on the positive terminal, and run it to the positive cable that's connected to the starter and turn the key. If it starts, then you know the solenoid is probably fried. If even that doesn't start then I'd start looking somewhere else, like the condenser and the ignition switch. Something along the line got fried. Knowing the guys in here, I'm sure they have other solutions that are more sophisticated. Me, heck, I'm a redneck.
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? As long as the power cable didn't touch the ignition wire (spark plug wire) your coil,condenser,points (if you have them) everything on that end of the system should be ok. but the fuse going from the solonoid to the ignition switch (or amp meter) may be blown check this fuse the engine will still turn over but you will not get spark.
quote:
Its not hard to overlook the obvious when its too simple to be the problem

It only hurts till the pain goes away
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I don`t see how that fuse being blown would cause it to lose spark? The spark comes from the magneto as it passes the magnet on the flywheel it is not a battery ignition. I have had that fuse blown and the engine wouldn`t turn over.
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After thinking about this, I would also check the wires going to and from the coil. Not the wire going to the plug, but the smaller wires. One goes to the condenser and one to the switch. If one of those wires are grounded, that will stop spark. They are smaller diameter wire and could have heated up quickly to melt the plastic and thus grounding the wire.
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I'd 2nd checking the plug. The plug wire connects to the high voltage coil secondary, which is relatively high resistance. I don't see how you could get enough current to flow there to weld anything to the plug. To the plug side wall, for sure you could weld it as that's grounded. So maybe the plug itself was shorted? Otherwise, as Elon said, you're going to find some melted wires and the high tension wire is going to be fried. But I still don't think you could get enough current into the high voltage side of the coil with 12V to hurt anything. Let us know! I even considered trying this on one of my engines but talked myself out of it. -Don
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As I understand what you have done is that you had the spark plug wire off, then while turning the plug you hit the 12v lead wire going to the solonoid causing a ground fault this inturn welded the wrench to the terminal on the solonoid. in as much a direct ground short from the battery to the sparkplug ground. The resistance would be a direct asault on the battery terminal and anything connected to it. back bleed of voltage may have surged the battery the solonoid or the key switch from the key switch it would possably bleed to the ground of the coil (kind of streching here though)
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