454 engine in a '87' Holiday Rambler motorhome, engine runs great except on some occassions after the engine is turned off gas will leak out of the (I think) it's the vapor recovery canister. There is one large canister with multiple hose connections with one of them going to a smaller canister filled with charcoal, which is where it leaks gas. Enigne has 4 barrel carb. Any help greatly appreciated.

Likely your carburetor float bowl is getting over filled with fuel. The excess fuel is running down the vent line and into the cannister.

The float may be adjusted too high, or the needle and seat is leaking, or the float itself is saturated with fuel and is starting to sink.
Either way, I would suggest a carb rebuild and a new float.

Thanks for the input. The carb rebuild sounds like the best bet, it's the original carb and has never been serviced other then filters and vaccum hose replacement.