Small Engines (Lawn Mowers, etc.): B&S 17.5 hp B&S engine runs cold for 2 mins, then dies, solinoid, air leak

Question
Hello!  My 17.5 hp sears lawn tractor (purchased in 2003) began giving me trouble a few days ago.  When cold, it runs strong for a few minutes and then begins to stumble and dies.  It will not start back up right away.  After allowing to cool for about an hour it starts up, but dies shortly thereafter.  I replaced all of the easy stuff: air filter, fuel filter, battery, spark plug.  Didn't help.  I now suspect magneto or fuel solenoid.  

Engine model is B&S 31C707.
Engine type is 0230-E1

Thanks for your help.


Answer
Doug
Most likely it is a fuel problem if the magneto was bad it wouldn't start at all.
Check to see if the fuel solinoid is staying open while the engine is running.
Also If the machine won't start and the spark is good, you must make sure that fresh gasoline is getting to the carb. Make sure that the fuel shutoff valve (if present)  is opened, and that the fuel line is not plugged or kinked. Also be sure the fuel cap vent is open and any screens in the tank are clear of debris. If fuel can flow to the carb, carefully place 1 teaspoon of gasoline down the spark plug hole (or a add shot of starting fluid into the carb throat). Re-tighten the plug and try to start the machine. If it runs for a second or two, then quits, chances are the carb needs to be serviced (disassembled and cleaned & inspected, then rebuilt) or you have an air leak somewhere. Make sure all mounting screws or bolts are snug and gaskets are not missing sections. If the carb is a bowl-type check for water in the bottom of the bowl (but do not let the float swing all the way down or the float needle will fall out!). It is easy to install a carb kit yourself.