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I would try a plug first. If it was wet, it may be fouled out and not sparking under compression.</div>
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Brian</div>
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Nampa, ID</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Shop-talk <shop-talk-bounces@autox.team.net> on behalf of Jeff Scarbrough <fishplate@gmail.com><br>
<b>Sent:</b> Wednesday, July 2, 2025 12:31 PM<br>
<b>To:</b> shop-talk@autox.team.net <Shop-talk@autox.team.net><br>
<b>Subject:</b> [Shop-talk] It's A Simple Machine, Right?</font>
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<div dir="ltr">I've got a puzzle...
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<div> tl;dr - should I try the plug first, skip ahead and replace the coil, or is there something else I should try?<br>
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The patient is a Snapper rear-engine riding mower, a machine that's as simple as can be. Powered by a B&S Intek 12.5 HP engine, another simple machine.<br>
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My friend was cutting his grass and managed to get the grass chute tangled up in some old fencing. He got it loose, and continued to mow. After a short distance, the mower quit running and would not restart.<br>
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I brought it into my shop and we started troubleshooting. I first tried ether - it seemed like it tried for a second, and then nothing. Pulled the plug and it looked wet. Turned the engine over with the plug connected and grounded, and observed a spark.
Not a magnificent spark, but a spark.
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<div>Verified compression, but due to the position of the muffler, I could not get *any* of my compression testers to seal in the hole well. But it pushed against my finger with some force.</div>
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<div>Moved to the carb. Pulled and inspected. Float working, jet clear.</div>
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<div>Put it all back together, and nothing. <br>
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Pulled the ground wire off the magneto coil and no change.<br>
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So, I'm thinking weak coil. Not completely dead, but not working under cylinder pressure. Something else I read suggested a bad plug - this one was installed a month ago and has been working. Date code on the engine indicates it was built on April Fools
Day, 2008.<br>
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In the era of $15 lawn mower coils, I would throw one on with no qualms. But at $40 or $50, I hesitate.<br>
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So, tl;dr - should I try the plug first, skip ahead and replace the coil, or is there something else I should try?<br>
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