If it were an ordinary push mower, I would say flywheel key. Fairly common if
you hit something and stop the engine suddenly. It might have a spark, but the
timing would be off. Just a thought.
Sent from my iPhone
> On Jul 2, 2025, at 1:55 PM, Jeff Scarbrough <fishplate@gmail.com> wrote:
>
> 
> I've got a puzzle...
>
> tl;dr - should I try the plug first, skip ahead and replace the coil, or is
> there something else I should try?
>
> 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.
>
> 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.
>
> 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.
>
> 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.
>
> Moved to the carb. Pulled and inspected. Float working, jet clear.
>
> Put it all back together, and nothing.
>
> Pulled the ground wire off the magneto coil and no change.
>
> 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.
>
> In the era of $15 lawn mower coils, I would throw one on with no qualms. But
> at $40 or $50, I hesitate.
>
> So, tl;dr - should I try the plug first, skip ahead and replace the coil, or
> is there something else I should try?
>
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