2nd gen ram 1500
Vapor recovery canister. Or also called charcoal canister. The gas tanks has a vent to it, and the canister collects fumes, when the engine is actually running, the PCM will open a valve to suck the vapors out of 'em, and burn 'em. Its an emissions thing.
It *should* be... The Fed requires it.... but, they require cat converters too, and folks "lose" those on a regular basis. It's just a bunch of vacuum lines. Some larger than others. Shouldn't be too much of an ordeal to make it work.
I know this is a little bit of an older topic but I ran my 01 3.9 ram many months and never fixed my canisters lol....on mine a common fault was the old rubber hose just wearing out and setting an emissions check engine light, I suppose if your area checks for that kind of thing it'd need to be fixed but mine doesn't and it never hurt the truck any that I could ever tell :P







