70' C10 break line help??

[Mrmadmanmill]

I'm Getting ready to run fuel lines and i am a little confused. Based on what i can tell from LMC, there are two sets of lines from the gas tank. I have already done a rear tank conversion, so my tank is mounted in the back as in the picture attached... what confuses me is the return line. I have a standard mechanical fuel pump and all it has is the line to the carb and an inlet from the tank.

where does the return line go to? It has been a long time since i tore my truck down and i do not remember where the return line goes... Any help or images would be greatly appreciated!!!

Thanks

[oldiron]

The return line is used on fuel pumps with three fittings. I believe that in 1971 these pumps were used for emission controls. If you don't have to have the truck checked for smog controls I would leave the return line off and stay with the single fitting fuel pump.
Since I only have experience with 3/4 tons they were not required in 1970 on C20's.
Also use a vented fuel cap when using just the feed line only or you will have a collapsed fuel tank with a non-vented cap.
I noticed that you do have the return fitting on the fuel tank. Your choice of either capping off the return fitting on the tank or install the fuel pump with the return fittin on it.

[scorchingeng]

On mine here is how it is... hope it helps.

If you are running a recirc. electric fuel pump setup for fuel injection a line is provided for that return (the one on passenger side).

One port on the driver side is simply capped off.

The other goes to the fill kneck for venting purposes when fueling.

Good luck.

[THE BOSS]

i was told there is/was vent line that went to a carbon or charcoal canister on the core support from the tank.

i plugged mine off and checked to be sure the filler cap was vented

hope this helps you.