>The downside is that you can't change tanks if one is damaged, or
contaminated.
This aspect of the main/reserve tank system is what bothered me, Rusty.
Possible issues might be that someone puts a contaminate in the main tank,
or some crud blocks the fuel feed on the primary side. Also, a damaged pipe
or fitting allowing the pump/s to suck air. For lots of reasons, I decided I
wanted two fuel systems where each was as redundant as possible. There seems
to be no "right" way to do this one. Every approach has its pros and cons. I
went back and forth on this for a long time, and ended up with what I think
is a good solution.

I have independant tanks, pumps and filters leading fuel to a T just before
the rail. No fuel valve and independant switching of the pumps on seperate
batteries. The return is plumbed to a solenoid which defaults to the right
tank when off. When energized the return flips the fuel to the left side. By
switching the solenoid off when pumping from the left tank, or vise versa, I
can transfer fuel as needed. I'm wiring a crossfeed warning to prevent
inadvertant crossfeed. Ideally I should put check valves before the fuel
pipes T at the firewall, but havent done that yet.

Regards,
john Slade