I use to design fuel tanks and tested them.. the first EFI car was the Imperial the group that did the
injection didnt pay any attention to being low on fuel.. once they seen this issue we were given the
project to fix it.. after a few weaks we came up with a can inside the tank.. over time we came up
with a plastic reservoir in ALL production cars and trucks... still in all.. we called it a swirl can that
would use the return fuel to keep the can full.. the pump is inside the can and will drain the tank
to about 250 cc or less.. just look at the inside of a newer car or truck
EDIT
I also did a few company road race sponsored tanks.. they use to have a issue of running out of fuel
so we put 4 pick ups in the tanks we built(one in each corner) being that these were carb system they
never had a problem.. these tanks HAD to look like a production part.. we had to seam weld the seams
on them