If you are quite sure the filter in the tank is not blocked ( try with full tank and no filter connected ) its into the carb, the cover with the single screw is the pump side, there will be a gasket and a diaphram in that order, under here will be a fine screen, clean the screen,re fit the cover, the cover with four screws is the metering side, there will be a diaphram and a gasket in that order, once removed you will see the metering lever and needle, make sure the lever moves freely and lifts the needle, conect a fuel supply to the carb and depress the lever, you should get fuel now comeing through, if yes re assemble and try again, if no you will need to dis assemle the carb and soak in fuel, blow out with LOW pressure, be sure not too blow the screen out and lose it. With all pipes dis connected does the primer bulb return normally?
Husqvarna man, May 2010