Two things you can try

Check and see how many turns your screws are out.
Remove the screws and drip some fuel into the screw holes a couple of times and give it some time to work its way into the carb.
Replace the screws and it should wet the carb enough to get it to suck fuel.


Another way that has worked for me is to hook the fuel pump you use to fill the tank to the vent line.
Pump fuel into the vent line and pressurize the tank.
Loosen the line going to the carb until fuel starts to come out of it.
Ignition off
full throttle
choke on
give it about 10 or 15 fast flips.
remove pump from vent line
try and start engine like normal.