Small Engines (Lawn Mowers, etc.): Lawn Mower will not start, thanks for your help, debris

Question
lawn mower will not start. It is a walk behind Snaper Lawn Mower. When the air line is removed and hand is placed in a position to block air and then unblock air mower will operate but as soon as air line is attached mower will start and then cut out in about approximately 15 to 20 seconds.
As info Mower was repaired last year and I had about 8 cuttings before this problem started.
Thanks for your help. Richard

Answer
Hi Richard,

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.  

Let me know how you make out.
Michael