i wanted to revisit this issue from May this year.  My velocity plans
   call for a low, wide sump tank mounted on the cabin floor near to
the firewall.
   I would guess it is only a few gallons in capacity.
  Am I correct in abandoning the sump in favor of plumbing the system
   so that the fuel selector routes the return fuel back to the tank
from which it is drawn,
   as in your drawing below?  What is the purpose of the sump tank anyway?
jeremy solomon



No kidding. "A long wide sump". That is dumb. I guess you are not supposed to slip or make uncoordinated turns. EFI engines will quit right now if the fuel
pickup becomes uncovered. What you want is something like one of these illustrations.

No dwg was included. If you want one sump tank make it tall and skinny
mounted in the center as low as possible. Can be mounted on the engine
side of the firewall.

The purpose of a sump tank is so a one layer  selector valve can
be used and return fuel is sent back to the sump tank.

Paul Lamar