Yes the return line goes back to the pump. At least on the 4.0L it does.
Mine had the same issue. It was pinched where the lines go through the cross member just before the tank. Follow the lines after the fuel filter, you will see the cross member they go through. After time and rust the area that the lines go through get smaller pinching the lines.
My fix was to pull the lines out, cut them and run metal lines through that area. Have not had a problem since.
93 YJ SOA 2" springs front, XJ springs rear w/main leaf added, High pinon 9 inch rear detroit locker front Dana 44 ARB 4.56 Gears, 36 inch Irok tires too much to list. www.mijc.org