96 Blazer fuel delivery problems

I have a 96 Blazer that I just brought back from the dealer service dept. According to them, it needs a new fuel pump, tps, and a vent valve that's located inside the fuel tank. Thanks to the $1000 price tag, the dealer won't be doing the work. I have a guy who will do the work for me, but I've never heard of this vent valve in the fuel tank. Anyone know about this, how hard the work is, or where I can buy one?

You need to post a thread in the Chevy Blazer area, NOT the VW Lupo area. DO NOT POST IN HERE AGAIN ON A CAR THAT DOES NOT BELONG. If this was a mistake... Make sure you know what you are doing.