[FRED]

I'll revise my answer. Seems the vent at the bottom of the filller neck goes to the purge valve. There is another hardline under there that is spliced to the line that goes to the top nipple on the filler neck.

The HOSE at the top of the filler neck goes to a hardline. That hard line splits off and one end goes to the turbo inlet duct on the other side of the engine. The other split goes aft to that open hardline nipple you showed along with the two fuel lines with the worm clamps.

Sorta stare at the jpg out of the FSM and I'm sure you'll figure it out. Maybe that HOSE you see open goes to the bottom of the Purge valve?????