Fuel Line Disconnected!!!???

I was up under the car looking at the exhaust heat shield because it was vibrating, when i spotted a fuel line that was separated...I bought this car four months ago from a small car lot. Its a 1997 SC1. I started the car and no gas was coming from it, but i did smell heavy fumes coming from it, is this a vent hose of some sort? I reconnected the line but would still like to know what it does...Thanks.

I was up under the car looking at the exhaust heat shield because it was vibrating, when i spotted a fuel line that was separated...I bought this car four months ago from a small car lot. Its a 1997 SC1. I started the car and no gas was coming from it, but i did smell heavy fumes coming from it, is this a vent hose of some sort? I reconnected the line but would still like to know what it does...Thanks.

That looks like the fuel return line. Starting in 1998 models, the S-Series went to a returnless fuel system.