I have looked at using an EFI sump for my dual tanks, and the only question I have is how to handle the fuel return lines. I already have return lines on my mechanical fuel pump, and a six port solenoid that switches them. It would still work as designed for the mechanical pump.
If the regulator and pump for the fuel sump also needs a return line, do I need to run and switch another set of return lines? Depending on the pressure in the return from the sump, it could get complicated to find a solenoid to switch the return at the same time I switch from one tank to the other. Or maybe I’m just overthinking it.