Small Engines (Lawn Mowers, etc.): briggs 10 hp stops running after 15 to 20 minutes, gas filter, new spark

Question
Hello,late 80's briggs 10 HP, new spark plug,took carb out and cleaned it,new seat and niddle,took gas tank out no dirt,when this happens the gas filter is empty don't know why this happens. If you could please help.Thanks,Carlos. Cheked gas cap hole is fine,gas goes in by gravity tank is higher than carb

Answer
Hi Carlos,

Hmmm, you have checked all the things I would have suggested!  
Since the fuel filter is empty, I would think that either the fuel flow is stopping or air is getting in the fuel line.  Investigate upstraem of the filter.  The cap vent may be intermittant or the tank flow may be stopping.

Let me know how you make out.
Michael