I have an 06 gs500f,  there is a t coupler on the vacuum lines above the carbs.  One line goes to the petcock on the bike, one line goes under the right side carb, and the third line was leaking air.  Should the third line be connected to something or just plugged off?

what i found helpful was to look at the diagrams on bikebandit
here is a link http://www.bikebandit.com/2005-suzuki-gs500f/o/m16075#sch591349
BTW your question is hard to answer some photos would help
cheers

i will post some pics today.

isthe hose circled in red supposed to be connected somewhere?  also, should the ends be covered on the white things on the front of the carbs?

Anybody got any idea?

I think this is the info you are after...

I do beleive you are right, thank you very much!