My bus was acting like it was out of gas when the tank was about half 
full. I read in the Muir book that the first half of the tank flows out 
with gravity and the second half reqiures the pump. So I put in a brand 
spankin' new pump, everything's fine for about 2 tankfuls, and now it's 
doing it again! Assuming the pump is fine, what could be going wrong?

Any help appreciated,

--Jonny B-)