1987 evap system

I have been replacing brake lines on our old rusty Cherokee when I discovered the evap line from fuel tank is partially missing, rusted away near the back. I have never noticed raw fuel smell, but what issues will this problem cause? Can anyone explain the system to me? I will replace the line if needed which apparently involves dropping the fuel tank.

If it's the line I'm thinking about, it is a return from the evap canister up front and could be releasing gas fumes. Best to replace if you can.

Path is intake to evap canister and return to gas tank.