pausing a moment to verify my connections are correct

there are three fuel lines running along the frame. 1 leads to the canister (easy enough), the other two leading to the carbs.

which of those two fuel lines is supposed to be supply, and which is supposed to be return?

and why are the hard lines running along the frame 5/16", while the lines running to the carbs are 1/4"??!!

thanks,

tony

what kind of car? diagrams in FSM.

On the carbureted cars the feed line is 5/16" and the retrun line is 1/4". This is becasue the feed line, being on the "suction side", must carry the required fuel with less minimal pressure drop. The line after the pump has a higher pressure "pushing" the fuel and is much shorter so there is less resistance to the fuel flow.

the car is an early 260z. i dont have a set of calipers, but it looks like the supply and return lines are both 5/16.

Looking at your photo and comparing it with mine. The top one should be the return line. The middle one is your fuel supply and the third bottom one just visible is the carbon canistor line.

To be certain you could follow them back to the tank.

Chas

You can just trace the lines back to the tank easily enough. Otherwise, I believe the line to the left in your original photo is the feed and right is return. If I were you, I'd confirm by tracing anyway, you never know what a PO could've cobbled up back there...