68 GMC Sierra fuel gage/electric

[Captain J]

Greetings
1. My friend’s 1968 GMC Sierra fuel gauge is not working, I checked the wire from sending unit to the fuse box it was good, however the wire connection to the fuel box have no electricity at all (it plugs to the top of the fuse box it indicates fuel gauge)
Anyone knows why no electricity and how to check/fix/resolve it?

2. As I know, the 1968-1972 sending unit has only one fuel port that goes to the fuel pump, this truck has 2 ports, one is venting hose, however it’s inside the cab, and cab smells fuel.
Do I cap it, or do I extend the hose to outside and where?

Note: this truck is fully restored.

Thanks