Small Engines (Lawn Mowers, etc.): 5 hp Briggs and Stratton wont stay running, briggs and stratton, hp briggs

Question
I recently bought a used go-cart with a 5 hp Briggs and Stratton at a yard sale. It had sat for sometime and the fuel went stale, I cleaned the magneto, emptied the old fuel, changed the oil and put new fuel in it and after priming it it started and would run and even throttle up, but as soon the kids tried to run it and it would die after going only 20 feet, so at this point I removed the carburetor sprayed it with carb cleaner, replaced the diaphram, all gaskets and even replaced the fuel tube with the screen that inserts into the tank. Now the engine will not stay running unless I constantly spray fuel into carb. Any idea where to go from here, short of replacing the carb?

Answer
Although you sprayed carb cleaner through the carb, you need to also push a piece of tag wire through all of the internal passages and then follow up with carb cleaner.  Carb cleaner will not always dislodge blockages within the carb.  Then make sure you have re-assembled the carb correctly and set the high speed mixture screw to 1 1/2 turns out from lightly seated.  Hope this helps.