Reply to "Fuel Vapor Cannister"

The laws in the US regarding automotive air pollution included "evaporative emissions". The government test involved locking-up the car in an air tight room of a certain size, at a certain temperature, for a certain amount of time, and afterwards measuring the amount of hydrocarbons that had collected in that room.

In order to pass the test the evaporative emissions from the fuel tank (and in later years the carburetor fuel bowls too) had to be collected, to prevent them from entering the air space of the test room. The charcoal canister made this possible, it is where the fuel vapors could be collected during the test period. Once the engine was started fresh air flowed through the charcoal canister, induced by its connection to the air cleaner. The evaporative emissions collected in the canister should have been pulled from the canister and inhaled by the engine. That is how the design was intended to perform. It was (and is) purely an emissions issue, not a safety issue.

Whether or not you utilize the charcoal canister, I hope your De Tomaso's fuel tank vent will be equipped with one of those "check valves" that prevents liquid fuel from flowing out the vent if the car should ever become upside-down. That would cover the safety issue.

When I was a bachelor I kept motorcycles stored in my den, started them up in the house, and drove them around the living room. Fuel vapors? Never noticed them.