Carbon canister

H22A4 said

My 75 318 only has one hose going to the carb. The port on the canister that is closest to the passenger fender has a cap on it.

Click to expand...

It might be a canister for a different year vehicle. Mine has the "purge" port fused solid. I think it may be from an 89 Jeep or something. I put a canister purge valve, something like this http://www.autozone.com/emission-co...canister-purge-valve/68752_0_0/?checkfit=true

on mine where the smaller line (valve) goes to a ported vacuum source on the carb and the bigger lines connect the canister output to the carb. That way the carb only pulls fumes when there is a vacuum on the ported line.

Or, it could be stock and you have a different system...