Why do you need a vacume to the charcol canaster.
The firewall mounted canister catches fuel tank vapors. It looks like vacuum pulls the vapors back into the system to be burned off.
I put vacuum on my float bowl overflow canister for a couple of reasons.
1. To help evaporate the spilled fuel.
2. I thought a bit of negative pressure would help pull the overflowed fuel thru the hose and over to the fenderwell mounted canister.
