I'm baffled!

MrGbo

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Hello, I hope everyone is well.
I have a problem with my lawn mower that has completely baffled me. It's a 2015 McColloch M46-125WR with a briggs and stratton 450E engine. Earlier on in the year I replaced the carb as it was running very lumpy with more smoke than what should be normal coming from it and that worked a treat. Last week I was mowing and it gradually died (like it does when you run out of fuel).

At this point, I had a spark at the plug so as I had bought a spare carb at the time, I just put the brand new one on. It still wouldn't fire up. I then found there was no spark so I bought and replaced the coil. Still not firing up and still no spark! It had to be the small earth wire so I changed it. Still no spark! The magnets in the flywheel are fine too
I'm just wondering if anyone has ever came across this problem before and is there a fix? My logic tells me it should be working by now?

Thank you in advance :)
 

Scrubcadet10

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Unplug the kill wire (earth wire) from the coil and check for spark.
also, how did you set the air gap between the coil and flywheel?
 

ILENGINE

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And if you haven't already done it replace the spark plug. After 23 years in this business one thing that I have learned is NEVER trust a spark plug. Just too many odd issues that related back to faulty spark plugs.
 

MrGbo

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Hi, thank you for the replies. I set the gap with a folded peice of paper as I can't find my guages (after points were no longer used on cars I thought I'd never need these again!). I'll try disconnecting the kill switch wire.

I tried 2 different plugs but I can grab one from the car and see if that works. Years ago we used to just put a screw driver in the HT cap to check if the coils were working
 

Richard Milhous

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If none of this makes it work you might consider that the brand new coil could be defective. Did you check its resistance?

How exactly did you determine no spark?

I still have a dwellmeter in a toolbox, pining away for the day when I have a real car to work on again...
 

Scrubcadet10

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the trigger chips in the coils throw off resistance reading.
coils usually either
Work
Don't work
Work with the kill wire unplugged
Don't work when they get hot
 

Richard Milhous

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the trigger chips in the coils throw off resistance reading.
coils usually either
Work
Don't work
Work with the kill wire unplugged
Don't work when they get hot
Except when they deliver a half-assed weak spark that won't pass the Slomo test. Like that infamous Ariens thread, or that fellow who confirmed spark by grabbing the plug wire but it turned out the points were burnt. Or my '92 that would give me a jolt but wouldn't catch until I replaced the coil. I'm guessing the cause is shorts here and there in the coil secondary windings; the wire is after all insulated with what amounts to dry spit.
 

bertsmobile1

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Except when they deliver a half-assed weak spark that won't pass the Slomo test. Like that infamous Ariens thread, or that fellow who confirmed spark by grabbing the plug wire but it turned out the points were burnt. Or my '92 that would give me a jolt but wouldn't catch until I replaced the coil. I'm guessing the cause is shorts here and there in the coil secondary windings; the wire is after all insulated with what amounts to dry spit.
Think you missed the point Richard
They can not be repaired so either they work or they get replaced
 

MrGbo

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The coil I bought was from Mr. Bezos website. It's description is "OuyFilters OxoxO Ignition Coil Compatible with 593872 799582 798534 Compatible with Briggs & Stratton 08P500 08P600 093J02 09P600 09P700". I borrowed a multi meter from my neighbour (I really need to get one of these) and tested both the new and the old coil. With the multi meter set @ 20k Ohms the original coil is coming back with a reading of around 8.87 so there was nothing wrong with it :rolleyes: Same with the new coil too.
I detemined no spark by taking the plug out, plugging it back into the HT lead and leaning it against the block whilst I had the wife pull the cord.
 
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