Originally Posted by Truckracer

The most common reason a carb doesn't suck fuel when choked is caused by the pump diaphragm flappers being stuck closed due to being dry. The carb may need a rebuild kit but most times you can just open the carb and wet the diaphragm with some fuel and it will start working. The pump diaphragm is located under the cover retained by one large screw. If the carb has some run time on it, another common cause is the strainer screen being plugged. Again, this is also located under the pump diaphragm and it can be removed and cleaned with a bit of carb cleaner. Be sure the screen actually passes liquid as sometimes they get coated with a clear film that will not pass fuel even though the screen looks good. A third cause might be a stuck metering needle and this is located under the cover retained by (4) small screws. Again, a bit of gas shot under the diaphragm and manually moving the metering lever a few times will make it functional once again.

The carb may need a rebuild kit but if the diaphragms are soft and flexible they should be OK for additional service. Hope this helps.