Briggs & Stratton 18hp Just Died

KJMClark

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This is on our older (92) garden tractor. I had the tractor out in the field chugging away on a moderate horsepower task (disking), when the engine cut out. Usually when it just stops out in the field, it's out of gas, but this time it had a third of a tank. I went back to get more and filled it, but then it wouldn't start.

It's been a bit hard to start when warm for a while, so I let it sit for ten minutes and then came back to it. Nothing. The starter chugs away, but the engine never caught. I let it sit for a half hour and again, nothing.

The oil was fine, the pistons and valves were fine (took off the cylinder heads later), I tried spraying starter fluid down the carburetor, but that didn't help.

I wasn't getting great spark when I tried the plugs, so I replaced the plugs, but still not great spark and no ignition. So I replaced the magnetron, but still, not great spark and no ignition. I was expecting to see a sharp blue spark across the plug every turn of the flywheel, but it looked to me like good sparking with my screwdriver in the boot and against the block, but only occasional spark with the plug in the boot and grounded to the block.

Any guesses what I missed? I gave up and took it to the shop, but I'm thinking maybe the flywheel key was sheared? I didn't hit anything, but maybe the key was partially sheared already and finally went.
 

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jspwrplc

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What is the model type and code # on this engine?
 

yardiron

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I had an ignition switch fail and short power to the coil last fall on my YT16, which uses an opposed twin Briggs engine. The contacts inside the ignition switch fell apart or broke, sending 12v to the magneto coil which should only see a ground signal when key is turned off. I had to replace both the coil and ignition switch.
 

KJMClark

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Hey, sorry for not posting, I thought I'd get a note when someone wrote something. 422707 type 1214-01.

The shop says they *think* it was a blown head gasket. They're supposed to try that out and let me know, but that was yesterday, and I'm still waiting to hear.

BTW, they said the weak spark was just an old battery that wasn't spinning the flywheel fast enough. We'll see.
 

noma

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Hi If its just a weak battery that doesn't turn the engine fast enough then just put a charger on the battery with a little boost and that should turn it over fast enough for a short time just to try it and see if that is the problem, if so just get a new battery. Trying the battery charger would be cheaper then a new battery.
 

OrtisEvans

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Magnetron? You mean magneto? A sheared or partially sheared key would kill the spark, as would bad points (if it has them) or a bad magneto coil. If you get a good spark to a screwdriver but not with a plug, then you have a bad plug. They can look great, and still not work. I have had mice chew off the plug wire near where it comes out of the magneto. When I priced a new magneto, I soldered in a piece of wire, wrapped it wit several layers of nylon cord, then several layers of tape. Ten years later, it still works.

As someone else pointed out, check the wire to the stop switch, if it has one, If it is grounding out, it will of course kill the spark.

I may haave just spouted stuff you already know - if so: sorry and good luck!
 
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