Mercury 6 HP 4 stroke Carb vent lines?

[Trailtech]

My friend just brought in this motor and it revs up even with the throttle closed (suspected vacuum leak). First thing I noticed were the 2 uncovered vents on top of the carb and I wasn't sure if they needed to be capped off or routed somewhere. I assume one is for fuel overflow but I am not certain. I figured I would ask before I start tearing into the carb etc and help narrow down what the issue really is. Thanks in advance.