That small piece of nylon tubing is the pressure reference line from the fuel pressure regulator. It routes from the FPR under the inlet manifold and to a nipple molded into the crankcase vent line from the valve cover to the air cleaner.

If the FPF leaks the fuel will be vented to the PCV system and consumed by the engine. The nylon tubing becomes brittle with time and breakage is common.

Duke