Using all kinds of fuel cells and or gas tanks we have run across the same probelm that was just brought up in another thread.
Yes, loose nuts bolts, poorly installed fittings, improper routing of vent lines, plus a multitude of other problems can "smell" up your entire car, let alone just the trunk area.
What is shown is actually an early model (90's ?) Ford OEM EFI roll over gas tank valve. The hose runs to the bottom of the trunk floor and outside. Obviously acts as a vent but does not allow any fluid to pass.
I have used it in plastic, aluminum, and steel gas tanks. IF you decide to use one make sure you order the accompanying '0' ring/seal that goes with it.
Please.....common sense to install!
DV