Check the fuel inlet and clean this out. Also check the float and the main jet. If there is a clog in any of these items, this will cause your issue. I recommend taking the carburetor off the engine soaking it in carb cleaner and blowing out the passageways with compressed air.

You clogged the fuel inlet or stuck or damaged the floats .

Check the gas cap.

Same thing happened to me. Remove the gas bowl, float & needle valve. Spay with some "Gumout" carb cleaner with the straw provided on the can. Work the straw into every passage way, down carb throat and needle valve "seat. Put it all back together. That Ethanol in our gas is just awful on fuel lines too.

Floats good check it for I put it back together and you can flip the carb up and down and here it moving I cleaned the inlet on the pump when I had it apart it looked fine. Ive rebuilt several carbs and never had this issue. I know there gravity fed so I primed the line and heled it at the heigh of the inlet it flows for a second then stops so I primed it and pointed the line at the ground and got continuous flow. Whats weird is I ran the line in the exact way the stock line was ran

I have a craftsman riding mower with a 16hp Briggs & Stratton v twin. I put new gas line on and rebuilt the carb now all the sudden the carb isnt filling with gas I can pull the line off put a priming bulb on and get gas flowing no problem. I pull the priming bulb off gas still flowin out of line put it back on the carb turn the engine over for about 30 second un screw the drain bolt out of the bowl and no gas is in it