Is it a vacuum tube?

[taking_forever]

Putting an SR20 in the S13 and I'm trying to line up all the vacuum tubes and such, but I can't figure out a random line. Where my air box used to be there is a rubber line, connected to a hard line, which runs to the firewall, across to the right side, and back under the car to the fuel tank. I know it's not a fuel line, I just can't figure out what. Any ideas?

[NIK90s13]

It sounds like it goes to the carboncanister.

[projectRDM]

Fuel tank vent, used to go the charcoal canister. Remove the underhood portion and leave it vented.

[g6civcx]

Fuel tank vent, used to go the charcoal canister. Remove the underhood portion and leave it vented.

You can also remove the hard line and reroute the vent line from the fuel tank with a breather filter, or just leave it. Whatever you want. Just don't plug up the vent line because the tank needs it.

From the tank, it goes vent hose, one-way check valve, another hose, then hardline to the firewall and finally to the carbon canister area.

[s14slide]

I plugged mine, haven't had a problem yet. I got a JDM s13. Drove all the way to Ebisu, 4 hours. Vented at the track. Refilled, ran for about 5hrs on the track, revented. Same thing home. Never had a prob. If your that worried about it, just loosen your gas cap once at the beginning and end of the days drives.