No it's not suppose to happen. It just does because of the terrible design ford used.
Yes the easiest fix is to not drive delow a 1/4 tank. As a rule of thumb I never do on any vehicle so it's never been a problem for me.
Doing a real fix would entail pulling the fuel pump unit & modifying it yourself. If you go this far you may as well just replace the pump with a better unit.
