You put your finger over the hole on the muffler to pull the fuel over to the carb, when you are first trying to start it,try doing that first. With a starter box it should pull the fuel in there very quickly. Might also be too long a line between muffler and tank, or between carb and tank. Make absolutly sure lines are hooked up correctly, and sealed tight and in perfect working order. Perhaps dribble a bit of fuel into carb and see if you can start it then, once it's running it should have no problem at all pulling the fuel.
Jag