Tractor starts then shuts off, smell flooded

it sounds like a bab coil or electronic ignition.

90% of vertical shaft engines use the same pattern only seen a couple that one hole is off place

check the solenoid on the bottom of the carb check for movement and power if it moves and has power open the carb and clean it

Test for spark. Make sure the air filter is clean. Then make sure fuel is getting from the gas tank to the carb. Old rubber fuel line deteriorate and stop up small ports and parts in the carb. An inline fuel filter is a good idea on these larger engines. Sometimes, a larger B & S engine needs the OH valves adjusted to start easily and run properly. If after attempting to start, does the new plug get wet or even smell like gas? You should always use gas LESS than 30 day old. Gas goes stale like bread and milk. You can remove the fuel line from the fuel tank at the carb to drain old gas. You can also remove the carburetor bowl to check for water and sediment (which need to be cleaned out). Check these things and post back.

First check fuel shutoff valve on bottom of carb . Disconnect and remove , clean witn carb cleaner and be sure there is power at wire when the key is on . Also clean carb jets and bowl .....

Probably a leaking float valve. If it has a fuel shut off, use it, and run it out of gas after each use.
If you pull the bowl off the carb, it's the valve attached to the float. cleaning it may help, or replace it.

Same thing happened to me with my 26 horse kohler craftsman. Replaced EVERYTHING (spark plug, fuel filter, oil filter, and degunked the carborator), and still was flooding. It ended up being the flywheel key. Cheap part, quick fix. I guess it can happen when you hit something hard with the deck, or it can just happen without reason... I hit a snowbank hard with my snowblower attachment, but I didn't even realize it until afterwards because it kept running fine. Supposedly, even after the strain to the engine, it won't always stall out. It will keep running (but maybe rougher) until you shut it off. Then when you go to start it again, you will have no luck because all the timing is out of whack. It cost me $80 to have a repair company fix it. I think the part was only $5.

Have you checked for a good spark from plug, if in doubt replace spark plug.

It is flooded my friend, probably due to the float in the carb bowl is stuck.Take the bowl off and see if the float moves freely, check and see if the the float is still fuel free, if the float is sticking you will have to remove the needle and seat valve and clean, check to see if the valves o-rings are in good condition. use fresh fuel.

does it turn over slow or fast if it turns slowly thats the problem so it could be battery or starter they have to have a good amount of rpms to burn fuel right when starting if not it floods out the engine with gas hope this helps thanks wade