Joel cogitates:
> why another fuel pump? cause if you don't have some sort of valve or pump,
> the fuel in the (higher) rear tank would flow all the time into the (lower)
> front tank ... and i think it would flow a lot faster than you could use it!
> 
> i suppose you could fix it up where the standard fuel pump would pump INTO
> the rear tank, and the engine would always take fuel FROM the rear tank, but
> return it to the front tank. that way, you wouldn't need a filler neck for
> the rear tank ... just run the pump while filling the front tank (then shut
> it off when you fill the rear).

The simple route over this hurdle is a cheapo 'fuel tank 
switch/valve' that nearly every vehicle with two tanks has.  It can 
be electrically activated or manually turned but the whole idea is 
that it ties your two fuel tanks together BUT the internal valving of 
this gem prevents fuel crossover from one tank into another.  One fuel 
pump.  Two tanks.  and a Partridge in a Pear Tree
-dan