Mine kept loading up with fuel. Which = raw fuel fumes dumped into the engine bay. Not good. A replacement canister was $$$. Once they get saturated with fuel, they don't really ever "dry" out properly. Kinda like Baking Soda for the smell in your fridge. You can shake it and "help" it, but it's better to replace it when it becomes sautrated.
I ended up capping the lines and removing it all from the car. I do get pressure build up in the tank, but it made it through a very hot summer with no problems.