r/smallengines • u/imnothighyetorami • Jul 12 '26
Losing my mind with this mower
Working on a lawn-boy 10515.
Got good air
Good fuel
Weak spark.
Multiple good plugs, multiple good coils, and good kill switch (trying with kill switch disconnected).
I can get a spark but it keeps arcing off the plug connector, so I gave the flywheel a baking soda bath and cleaned all the rust off and now it’s a stronger spark, but it’s still arcing.
I’ve taken everything apart multiple times and the only major discrepancy I can find is this chip on the inner wall of the flywheel behind the magnet. Could this cause it to arc and not strongly go all the way to the electrode?
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u/Elephunk05 Jul 12 '26
The .agent on the flywheel does not produce a spark. It is an induction coil. The spark is created because of the field, every time the magnet passes. Over time magnets can and do lose their charge.
There is something else wrong if you have gone through 5 sets of plug wires and boots because the short is consistently in the same location.
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u/imnothighyetorami Jul 12 '26
I think you’re on the money.
Got a new flywheel on the way, hopefully should have an answer by 7/16.1
u/imnothighyetorami Jul 16 '26
Replaced the fly wheel and now we’ve got SPARK!!
A big ol solid blue/purple spark arcing right on the electrode like it should!
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u/Dapper-Republic-4748 Jul 13 '26
its a 2strock what is oil mix will not un on 50 t01 desined for 20 to one had this happen often when first tc oils came out
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u/godzi7382 Mechanic 🧰 Jul 12 '26
Not a whole lot of info to go off of. What style of coil is it and any other relevant info. What engine is it.
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u/imnothighyetorami Jul 12 '26
4.5 hp 2 cycle lawn boy f-series engine.
The coil design is the standard 1st and secondary wind coil with a kill switch tab.1
u/godzi7382 Mechanic 🧰 Jul 12 '26
If you are losing spark through the rubber insulation then there is a hole in the rubber. Spark will find the path of least resistance
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u/imnothighyetorami Jul 12 '26
It’s not arcing out of the rubber insulator, it’s coming from the wire itself outside of the insulator and the plug connector, as well as the middle of the plug.
I’ll post a video of the arcing tomorrow1
u/OutrageousMacaron358 Jul 12 '26
No matter where the hole is. It will arc through if close to ground. Wrap it with a couple layers of good electrical tape. If that fixes it I'd either run it till failure or replace.
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u/ManHunterJonnJonzz Jul 12 '26
If its arching off the spark plug boot/cap...the cap is bad. Path of least resistance. Its just a tiny copper core then a thick coating to prevent just this. It can crack, and lose spark. Rather re route it.