Little blue "valve" over fule tank

[xtraworx]

Because I have a cab over chassie configuration, I may be able to see things the rest of you can't. Peering down between the back of the cab and the front of the stake bed, I can see the top of the fule tank. Laying there is a light blue 'thing'. It looks to be some sort of valve. One end is connected to a black plastic hose which appears to snake its way to the fule tank. The other end is not connected to anything but looks like it is ment to be -- it has a graduated conical design, like a hose fitting.

So my question is, what is this thing and should the free end be connected to anything?

[chaozz]

i know this does not answer your question ill look over the manual
see what i can find ..my guess its just a vent

http://www.gotsinister.com/fueltankpic.jpg