gas tank venting problems

[restomodmusclecar]

I had not had any issues for a few years until this weekend when the gas started leaking from the check valve after sitting (motor was cold), the weather was pretty warm. The car also seemed to cut out a bit. I opened the cap I could see the gas level move up and down and bubble.  I've been told to run two different lines one from the tank and the other from the filler tube.  I've been told to go higher in the trunk and low above the axel.  What works?   Thanks Matt

Here's a picture of the setup
http://restomodmusclecar.com/wp-content/uploads/2019/10/UNADJUSTEDNONRAW_thumb_52b3.jpg

[b5blue]

The tank vents from filler tube only on a stock 68-70 Charger. That vent is a steel tube that runs down the filler and through the trunk floor inside the rear frame section. Big block Chargers have 2 lines on the Gas sending unit, one for fuel and the smaller is a return line from the vapor separator. 

[restomodmusclecar]

Thanks, for the reply.  I have the smaller return line only the previous owner bought a new one but did not connect it to anything missing the vapor separator.  Any suggestions?

[b5blue]

Plug the return on the fuel gauge/pickup if not used. What is that tee doing with the do dad to the right?

[restomodmusclecar]

One leg of the tee goes to the check valve down to the send unit port and the other leg goes to the filler neck vent. 

[b5blue]

Should just be a tube from near top of filler down through trunk floor. (Works as a vent/filler overflow.)