Originally Posted by toyomoho

If you look on the firewall there may be a plastic canister with hoses running to it. This is part of the cars fuel tank emissions system.

It stores gas fumes routed to it from the fuel tank in charcoal. When the engine is running, a valve is turned on to route the fumes to the engine.

The canister has a vent on the bottom to allow air flow when the fumes are being drawn out to burn. I thought there was a one-way check valve to allow air in but not out.

Might check this area, the hoses for damage, etc.