When replacing some vacuum lines I noticed one of my lines on my vapor canister is capped off and fastened to the instide radiator fan, kinda looks OEM however the vacuum chart (that is if I had the right one) shows a line that says "to fuel tank". I think that is the line, but am not positive.

I have also heard a woosh sound when removing the fuel cap.

It doesnt seem to be causing any problems other than the whoosh sound. It also seems like it would improve fuel economy by not venting to the atmosphere.

I have searched but havent found much pertaining to this particular issue, they just said not to mess with the EVAP system, and to be sure that the system is functioning properly. Can anyone shed some light on this?

Ill edit with pics later since ill be pulling my radiator and replacing it today.