Carb needle and seat maybe? That is what I would check. Works like a toilet water tank at your house. Low water the arm opens to lets water in the tank. Arm rises and shuts off water at a determined level.
This is an easy fix. New parts should be cheap if needed to fix. I would pressure test the carb with 7psi for 30 minutes minimum. Flip the carb over and test it out. Youtube has some good videos.