I was wondering to. Mine is a 4,2 with a MC2150 carb. It turns over more when sitting a few days. I run the fuel filter with the fuel return hose.
My son has the same carb on his Ford Ranger with no fuel return filter. His starts up a lot more quickly. So I guess it's psooible for the fuel to go back to the tank and drained up to the needle valve inside the carb. With the fuel filter return, after shut off, there should be no fuel pressure at the carb since it's vented back to the tank on the re.
I learned that the fuel filter return line, had to be at the 12:00 position, It was to keep fuel flowing to prevent line lock up from heat, and to releive the pressure from the fuel pump when it's not needed as much (idle).
Most Fords do not have return lines. So I am wondering if you have a carter or motorcraft, that the fuel return can be eleminated?
90 YJ, 4.2 with 2150 carb 4.0 Head and headers, Nutter with TFI and MSD. 1" BL, 2.5" spring lift, 33", Goodrich KM Mud Tires. Dana 30 w Aussie, Ford 8.8 w LS. 9000lb HF Winch.