If the engine has been sitting for a long time it may have a stuck inlet needle. Try this, ignition OFF. Full throttle and use your thumb or finger to completely close off the velocity stack then briskly flip engine over or use your starter. Once fuel gets to carb keep flipping 10 or 12 more times to fully fill the carb and get some gas into the engine. If you then open the choke and close the throttle to a high idle setting and hear a wet snotty sound as you turn the engine over you are good to go.

If that doesn't work I have done this; Remove the carb and both the pump cover and the metering diaphragm cover, gently remove the associated diaphragms and gaskets as well as the filter screen. If you are careful they can be reused without any problem. Now put a drop or two of 2 stroke oil into the hole that the filter screen was in then depress the inlet needle lever arm to force the needle open and allow the oil to flow through and around the needle. Wipe off any excess and reassemble carb wiping a bit of oil on the pump diaphragm as well. Give it another try.