[Butcher]

Is there supposed to be another knob that closes the hole on the canister? Also what does the canister do? Its on a 1990 2.3l

[Green Ghost]

it is the charcoal canister: the system is designed to prevent hydrocarbons from being released into the atmosphere by trapping and storing fuel vapor from the tank.

[92'Grey-Ghost]

Originally Posted by Butcher

Is there supposed to be another knob that closes the hole on the canister? Also what does the canister do? Its on a 1990 2.3l

Yes, its a vent tube that runs from your fuel tank. There should be two caps on it, Its a cap that still lets out fumes out of the bottom of the cap (kinda mushroom shaped) designed to let the vapors out, but keeps the canister from getting water and such on the charcoal. Just twist the other one out to see what I'm talking about. You can get one at a salvage yard.