Two things may be happening, one is the fuel evaporating and the accelerator pump may be the wrong size, to small Many of the over the counter cheaper rebuild kits come with the gaskets and accelerator pumps to fit many different carb application so the maufacturer doesn't have to have 12 different kits to fit all the AVS Carter carbs. made for OEM carbs. the other thing to check is the accelerator check valve sticking in the channel under the accelerator pump squirter Pull the carb. off so you can tip it upside down over a clean white towel or white paper towels to see if it(brass check valve) drops out easily or not Todays gas with Ethanol in it eats alumminum so it may be stuck in that passage