I was over at a friend's house looking at my car and we found a hose that was plugged off. This was on the passenger side of the engine bay and ran back down the frame rail.
My friend's dad said that this hose may have gone to a charcoal cannister and the previous owner had plugged off the vent tube and tossed the cannister.
Your friend's dad is correct.
And would this cause a problem with fuel pressure? I saw a few threads about people using old fuel filters to vent the tank and keep out bugs.