I have a problem getting fuel into my carb and I suspect something in the carb is the fault.

When I turn it over and the fuel line is connected to the carb, the fuel does not move through the line. if I remove the line from the carb and turn it over, the fuel flows very well through the line. I checked the float bowl last night and it is very clean. I will be removing the carb tomorrow and doing a full check but is there something else in the carb our out of the carb that I should be concentrating on?

TIA