There seems to be a blockage in the fuel supply. You will need to strip the carb and clean it, make sure that all the jets and the needle and seat are clean and the needle moves freely. Blow out all the ports and passages, be careful, there are some very small parts in a carb that can easily be lost. Also check the diaphragms for cracking and perishing. It might just pay you to install a new carb kit while you are about it.