What you need to remember is that the fuel bulb pulls fuel from the carb, into the bulb and dumps back into the tank, you will get an amount pressure in the tank, the return hose only needs to sit just inside the tank, it does not need to sit in the fuel, if you have the pipes correctly fitted the only way it can drag air is if there is a leak in the fuel hose.
Husqvarna man
May 2010