There seems to be some varied opinions as to weather or not not the 122 fuel tanks are suppose to be pressurized. Over the years I've had four and they have all had this trait, but of course...
It so happens I have a see through filter as well (located on the carb side of the fuel pump) and there is always fuel in it. I think the pump acts as a check valve it its in proper working order.
I've heard that the 122 wagons are notorious for leaking gas out of the inlet, esp when the tank is near full and/or the car is parked on a hill. Although I have a sedan I have learned never to totally fill the tank (mine leaks at times through the sending unit area at the bottom of the trunk).
Whenever there's a "leak" anywhere in the fuel system you will likely smell the fumes. And if you look at the tank from underneath, and at the bottom of the trunk, you might find the source.