Gas Tank connections

Hi everyone. I am new to this site and a proud new owner of a 84 KZ700. Glad to see such a great site dedicated to such a cool series of bike. Picked it up for $500 bucks and ready to get her going. It is complete but some parts are in boxes. I guess the first thing i noticed was the connections on the gas tank. It has the fuel connection, a vacuum connection, and then another connection that looks like some cover with wiring harness coming out and a vacuum style connection tube. NO lines at all on the carbs, I have figured out the fuel inlet on the carbs, but dont know where else the connections go. Is there any diagrams somewhere? Is that cover something for the fuel guage? Any help is greatly appreciated and will post pics as soon as I get them.

If it's below the fuel sensor, it's probably a line to safetly let dripping gas get below the bike, if the tank sensor developes a leak, preventing gas on a hot engine.

Yes, it is attached to the fuel guage cover. It looks like it had a hose on it at some point and I dont see anywhere else i am missing a connection so I think you must be correct. The weird thing is that I put the fuel system back together and the guage didnt move. Wondering if that connection has something to do with it or possibly just have a blown fuse. Still have to check it out. Thanks again.