Fuel Lines

[GRN_VAGN]

Just wondering if there is a quickish way of finding which line is the feed line and which is the return line.
Tank is empty and i wanna make sure i got the lines right before i put fuel in.

Ill be taking backseat out and pulling that cover up to try trace it back and see which is which.

its a 78 GLS btw, small hardlines both same size, and its top feed on the tank, not side (which im used too )

[GeorgeMK1]

Was going to say, suck on it 'till fuel comes out, but saw your comment of no fuel haha