I hit a plastic sewer cap on my Craftsman riding mower (BS 28R707, I/C 13.5hp) and it continued running fine. 1 week later on the very 1st crank it starts to fire but doesn't; every crank since no spark, nothing.

I have heard this could be a Magnito (sp?) problem due to the strike. I went to take the flywheel cover off to look around and that removes the plastic oil fill tube. So I drained some oil out to keep it from overflowing...seemed thin and it smells of gas. Is there a bigger problem here or could it be from cranking so much I've thinned the oil from unburned gas in the combustion chamber (I've recharged the battery once b/c of test cranking so much). When I remove the spark plug I can smell gas as well after cranking.

Additional info, my Heat/AC guy neighbor says there is an open circuit on the Magnito lead and gives me a fusable link to replace it with. We uncover it and it doesn't look like a fuse (After reading tonight I think it is a 'ballast resister' to drop the voltage). Anyway we replace with the fuse link...only 3.5 amps...it blows right away. He thinks the strike may have messed up a ground/there is a short. What do you think?! Thanks for any help!

Sheared flywheel key

possibly a bent crank too but we hope not..........but peppy is right, you are DEFF goin to need a new key

Key for sure....., these (if its newer than 83) are just ignition coils..... nothing more or less. I've seen briggs hit harder things than a drain pipe and still go, but this doesn't mean yours hasn't sheared the key.... btw, just remove the kill wire to leave out any kill switches

It also sounds (if the oil smelling like gas) it could have messed with the fuel floats operation.

Thanks for the replies. I've gotten the flywheel nut off and can see the key. It looks okay, but I'm going to pull it anyway and replace. I've got to get to the stator underneath.

I've learned what the parts are now at least. It has a Stator under the flywheel and that is the line we put the fuse link in that immediately blew. So I guess I gotta replace that, or at least the wiring harness.

It also has an Armature/Magneto next to the flywheel. We didn't mess w/ those wires. I guess they are just ground wires anyway. How do I test the armature? I suspect this to be the real problem, since I get no spark at all, not just a mistimed spark.

Oh, and what/where is the easiest way to remove the kill wire? It's got push button switches in three locations that must be depressed to start.

Just take the shroud off, and pull the kill wire off the coil.

Thanks for the feedback. It turned out that when I took the Magneto/Armature/Coil off the face was pretty corroded/rusty. I sanded it real good as well as the magnet on the flywheel. Reset the gap w/ a biz card and pulled off the ground wire (didn't realize this is the kill wire?)...voila...spark! Reattached the ground wire, depressed all the kill switches...and still spark. Mowed the whole lawn and seem to be good to go.

I did reattach that diaode to the stator wire, I guess I won't know if we messed the charging system up for a while. I'll have to see if my battery stays charged.

Oh, I visually inspected the flywheel key, and was gonna replace it if the cleaning didn't work, but it looks fine so I left it alone for now.

I also changed the oil and put in a fuel line shutoff valve.