Triumph Repair: Fuel Tank, charcoal canister, vent line

Question
Hi Howard.  On my 1980 Spitfire there is an air vent line coming out of the top of the fuel tank.  This vent line goes into a black cylinder, about 3 inches long, which bolts into one of the top mounting bolts for the fuel tank.  The vent line then exits this cylkinder and the line goes to the engine compartment.

What is the function of this black cylinder?  Possibly some kind of a vent filter?  When I removed it and try to blow air through it, it appears to be plugged.

Thanks

Answer
Hi Jim,
That is a Vapor Separator to trap fuel from going on to the charcoal canister. It does have a restrictor on the tank end. With it off the car use compressed air to blow through it in both directions. It should let air go from the tank end to the charcoal canister end.
Howard