Vapor canister filter
If fine charcoal or larger bits can get out the top, they can migrate to the carb vent or into the gas tank. Carb vent is the worst because there's no filter to stop the stuff and once its in the bowl it will plug things up. So if you ever have carb problems and find little black bits in the bowl, that's what it is. Then open the cannister!
This is a Motorcraft 2150 carb with charcoal accumulating because the vent was open to the cannister while driving and the filters in the cannister had fallen apart.
Looking at the top of that Jeep's charcoal cannister with the charcoal removed.
As long as charcoal isn't getting through, then I can't think of any reason to open it up.
If fine charcoal or larger bits can get out the top, they can migrate to the carb vent or into the gas tank. Carb vent is the worst because there's no filter to stop the stuff and once its in the bowl it will plug things up. So if you ever have carb problems and find little black bits in the bowl, that's what it is. Then open the cannister!
This is a Motorcraft 2150 carb with charcoal accumulating because the vent was open to the cannister while driving and the filters in the cannister had fallen apart.
Looking at the top of that Jeep's charcoal cannister with the charcoal removed.