Siphon Gas?

Mine never evaporated a drop and I had it for 40 years, are you sure you do not have a leak somewhere?
You dont live in California with this new 'Gasoline" 20% alcohol. works good in a closed non vented system like a fuel injected system, But a Carb, it just goes away. every morning no fuel in the carb bowls at all. LOL, no leaks.