Cant get weed trimmer to prime?

its a craftsman weed trimmer about 1yr old and used only about 4 times total. i cant seem to get the fuel up into the "bulb". pressing the "bulb" does pressurize the tank, but cant get fuel to the "bulb". I have taken out what i think is the filter that is in the tank with no results. i have also blown air into the hose that is attatched to the filter and air does seem to be going through the system(nothing seems to restrict air flow). is there anything else i can try before taking it to the shop