Glad it was just the spring...that is a CHEAP and easy fix. I know it can be difficult to get to, but is much easier if you take the deck off....4 bolts on each side and it comes right off....just make sure to put a 2x4 behind the drive-wheel, you will see where a round steel rod comes off the side of the deck (it should have a rubber boot around it) and keeps the engine deck from swinging too low past the metal frame that the wheel is bolted to (probably doesnt make much sense, but look behind either of the drive wheels and you will see what I am talking about).
As for the fuel pump, you are correct...one line coming in from the tank, one going out to the carb (both carry fuel) and a vacuum line coming from the engine to drive the fuel pump...no fuel in that one, just vacuum from engine.
It sounds like your carb is dirty. You might try some Seafoam...I have not tried it myself, but know other people that swear by it. Otherwise, time for a carb rebuild and cleaning. There are several small passages in the carb that are easy to foul-up.
