Fuel Filter/Pressure Issue

OK, when I run it with the gas cap off the the filter gets almost completely full and stays that way. How do I unclug the vent tube? Assuming that's the problem.

What year/ model is your car? If its a 72, you can download a 72 shop manual for free right here:

http://www.forabodiesonly.com/mopar/showthread.php?t=132309&highlight=manual,+download

Judging from the photo, it's one that has the evaporative emissions controls (originally) I.E. the "carbon canister"

If so, these don't HAVE a vent except through the carbon can system. You need to get the proper year shop manual, and see how it's all set up.

If it's gone, there are "other ways." The original, earlier, "non" carbon can cars had a 1/4" or so line welded into the fuel filler tube up high inside the trunk just before the filler tube goes through the quarter panel. This tube then goes up high in an upside down "U" and then runs down along the filler, through the floor gasket, and ends (open on the end) inside the rear frame rail.

Like this: