gas vent on top of tank?

[npca-66-60]

So i am tearing through the back end of my truck getting all the lights and stuff rewired and I discover a plastic tube (1/2 -5/8 OD) that travels from the top of my gas cap, on the inside of the truck, to the tank. But.......when I really start looking at it the end above the cap is plugged with a metal piece and then I start looking around and follow the tube to the frame and its just tied off. I pull the panel above the gas tank to see if there is a vent. Sure enough there is and its fits the tube perfectly(length and size). I hook it back up and start thinking about why it would be like that. I recently got my patrol and whenever it sits in the garage a day or so and I go in there the smell of gas is pretty powerful. What is the deal.....I have the original carb and a new Holley pump the last owner installed. Any ideas?

[npca-abuelo442]

The vent in the gas tank helps when you're refueling, and it's crucial for it. Otherwise, it will be painfully slow to fill up. Could be the source of the smell in your garage.

[npca-67l60]

gassy smell  that's not good id be checking all my rubber hoses, and the fill neck especially  useing a standard quick disconnect fitting works great  just unscrew the main line and screw it in & apply  6psi and look and listen for leaks  youll be supprised  i test all my tanks this way  if you want to test the whole sys hook in to the vent hose you found   good luck with the search

[npca-honda guy]

yeah the vent tube goes to the filler neck and then right back out again, straight to atmosphere. it can be a source of fumes but a leak of some sort is also possible. I can say that a pressurized gas tank is like a huge bomb with a torch for a fuse. just be careful. i would just cap the vent tube and see if the smell goes away. then you know that was it.