Small Engines (Lawn Mowers, etc.): Backfiring, fuel flow, gas leak

Question
We are trying to figure out why my friend's 3 year old riding Craftsman mower will not start.  It apparently has not run in over a year.  When it cranks, it may chug just a couple of times and then dies.  Sometimes with a backfire.  My friend said he has seen gas leak out of the exhaust, which is in the front of the machine between the front wheels.  We changed the spark plug, it has a new battery, and I am suspecting the ignition coil (the magnet thing that is mounted next to the rotor?)  We were unable to get that part this weekend.  I was going to pull the block part of the engine apart just to clean the cylinder and valves, but the bolts were so tight that one of them stripped.  I realize that we may have to tap it out, but if we can fix the engine without having to do that, it will obviously be a lot easier.  Thanks for the help.  I really am happy to have found this forum, and think I may volunteer on the aviation portion.  Take care.

Answer
Hi John,

You will need to determine if the problem is a lack of spark or a lack of fuel flow.  Right after it quits, remove the spark plug, reconnect the wire and lay it against the engine head.  Pull the engine over and watch for spark at the plug's electrode.

If good, then try to start it while squirting fuel or starting fluid into the carb intake.  If it starts and you can keep it running by adding fuel, then the carb most likely has dirt, debris or gummed fuel inside.
You will need to remove the carb, disassemble it, clean all the small internal openings and blow it out with compressed air.   Probe each and every hole with a small wire.   A carb rebuild kit wouldn't hurt either.  

If the spark plug gets wet, then the carb is flooding and getting too much fuel.  In that case, the carb would need rebuilding also.

Let me know how you make out.
Michael