Small Engines (Lawn Mowers, etc.): Hi Michael, I have a B &..., water in the fuel, fuel flow

Question
Hi Michael,
I have a B & S 18 horse twin that when it would run for a while ( 15 / 20 minutes ) would stall and not start until it cooled off.  Now I can not get it to start.  Motor is in a 1992 MTD Garden Tractor.  Thanks for your help.

Answer
Hi Kurt,

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 no spark, check the saftey switches first, then replace the ignition coil.

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.   Adding a carb rebuild kit wouldn't hurt either.  

Another possibility if the problem is fuel related: Check the gas cap to make sure it is venting and not causing a vacuum in the tank.  Also check for water in the fuel.  

Let me know how you make out.
Michael