[jagrolet]

Ed
The point of the pump mounting position is that you can't always rely on the weight of the fuel to "push" up to the pump. Depending on the style of pump (vane,rotor,etc.),leak-thru for prime,may be at best,minimal. The upward loop of the line,is the air bubble,and alot of vane pumps,with internal regulators,won't let the air past by gravity alone.
Jaguar,on the XJS models,address this very intuatively,with a baffling resevoir and pump posistion.
thanks
wally