where does fuel return line connect to 1986 F-250 carburetor?

Question

changed 351w engine and C-6 trans. Return fuel line was not connected on the engine removed.

Answer 1

some carburated ones dont have one plug it off when you start the car look quick for a leak if none it doesent have one if theres a leak thats where it goes do it outside and keep an extinguisher handy

Answer 2

Some vehicles use the fuel pumps with the return line to help cut down on "vapor lock" during hot weather. It allows some fuel to continuously return to the fuel tank through a line in the top of the fuel sending unit on the tank. That way the pump is always pulling up "cool" gas from the tank and because of that circulation, has a supply of "cooler" gas to it at all times. This keeps the temperature of the gas that is going from the fuel pump on the engine to the carburetor slightly cooler than it would be otherwise. You have three options here. One has already been recommended in that you simply plug that extra line on the fuel pump. Another would be to get the sending unit for the top of the tank off a 351 model truck that has the extra hole for the return line to go back into. Third is to get a two line pump from a different year of 351 and replace the one on the truck. Bearing in mind though that if you either plug the line as suggested, or replace the three line pump with a two line as I have also suggested you might have more chance of vapor lock in the hot summertime depending on your local climate. An old trick for helping cut down vapor lock though during very hot weather is to take 8 or so old wooden clothespins and clamp them onto the metal fuel line running from the fuel pump up the motor to the carburetor at regularly spaced intervals. For some reason they cause an interruption in the heat of the line enough to break up some of the bubbles that form causing vapor lock when the motor is very hot. Didn't think this would work until I tried it on a old 69 Toronado that didn't like hot weather driving. :-)

Answer 3

There is no fuel return on carburetor (maybe fuel emission line to carbon canister?.... If so, plug it).
If your vehicle has no return line, then plug the extra fuel line connection at the fuel pump. I did this on a 72' F-250 with a swapped engine (85' Mustang HO 302), Its been running fine for 7 years. If your vehicle has a return line (going back to the fuel tank), hook it up to the extra fuel line connection at the pump.