Well, leave it to me to reinvent the wheel.
I found out what I have built is a dual flow rotating fitting.
Now you can buy dual flow rotating fittings, but they're expensive. You
can probably get them used from an agricultural junkyard, but I wouldn't
bet on it.
The good part about doing it
Change 1:
The 3/8 fuel line has too large an outer diameter to use as a lift tube
in the fitting built with 1/2 parts. It causes too much restriction on
the return side. I changed the inside hose barb to 5/16, and used 5/16
fuel line instead. This eliminated the restriction on the return
