For you electrically inclined riders:

I just did an overhaul on the Briggs engine of my old lawn tractor. It had been burning oil, other than that its been a great tractor. I got new piston rings, pan gasket, and head gasket for less than $50 at the local hardware store. That was the easy part. Got everything together and now I have no spark. I wither have a wiring issue somewhere or a bad coil i think.

This is a Magnetron Ignition system of course. Magnet is embedded into the flywheel. Only one wire (besides spark plug wire) is coming out of the ignition coil which sits beside the flywheel. Should this go to ground or should this be hot? Don't remember where I unplugged it from. Not sure if these systems run off the battery or whether they generate their own electricity with the magnet.

Magnet is good and strong, so if I have the wire connected to the right place, maybe a transistor has failed inside the coil? Please help!

 

Does this help? They generate their own electricity . The wire in question could be the left over points wire, if this unit is an add . In either case it should not be grounded. There will be one short one grouded to the top of the coil area. Too short to go anywhere else. Might be able to whip up a schematic if I knew the year/model.
Ron

 

There's a diode in the other wire running from the coil.. It's possible that is damaged.. Check your starter and system for ground.. There are a lot of possible causes but it's such a simple system you should be able to figure it out.. What size motor is it?

 

Its 286700 series Briggs. Was bought in the late 80's, early 90's. Looking at the schematic you supplied, maybe that extra wire I have is a cut out wire of some sort that stops the engine when you turn the key off? I see it goes to a stop switch on your schematic. I'm thinking that this is my problem since I have tried both grounding this and just leaving it disconnected. Neither case gave me spark. I will take another look when I get home from work. Should this wire be connected to the key switch somehow?

 

I can't find any better ref than the schematic already posted. Most magnetron systems however only have two wires. The sparkplug and the kill wire. With the kill wire disconnected it should run. Normal shutoff is done by grounding this wire. The coil needs to be set at about .010 air gap in order to trigger correctly or it won't fire. Failing that and since the coil has been off and back on for rebuild make sure you havn't pinched a wire between the coil and engine housing. Remember, with the kill wire disconnected from the shutoff switch none of the other saftey switches work, as in seat, deck etc. These units rarely fail, plus it worked before.
Ron

 

I know it is a strech, is it posssible that you have mounted the coil backwards to the engine block it could get the hall efect sensor out of timing so that it can not conduct while the legs of the coil are over the magnents. The extra wire is the shut down circuit which you ground to stop the engine.