Small Engines (Lawn Mowers, etc.): Only runs when full!, prime 20, shutoff valve

Question
Hi Michael,

I've got a 2 stroke Lanwboy walk behind mower that is 15-20 years old.  Fill it up, prime 20-30 times and it starts /runs fine.  Once the fuel level drops below an internal opening in the tank it stalls.  Add 3/4 to 1 cup of fuel to top it off, prime 20-30 times, and it runs OK again.  Any ideas?

Answer
Hi David,

Look inside the tank to see if there is a hose and fuel pick up on the end.  It may be hung up or clogged.  If not, try removing the tank and cleaning any filter, openings or shutoff valve, if present.  If that still doesn't help, the carb may need to be removed and cleaned internally.   

Let me know how you make out.
Michael