While working on the truck today I noticed the nipple on the purge valve was broken off. It doesn't look like the auto parts stores carry this unless I am just missing it. Is it necessary? Can it be bypassed? I can't really feel any vacuum loss there where it is broken. From my understanding it just sucks (purges) the gas vapors that are held in the canister into the intake to be burned. Will it affect drivability to not have it.