Have you ever had any work done to the fuel lines? Ever, at all? It sounds like the vapor line may have been switched with the vacumn line. The hose on the solenoid should lead to the throttle body, and the other hose to the gas tank. I'm not really sure if it actually makes that big of a differance, but check just to be sure. The solinoid may have also gone bad.
Because you asked, the purpose of the cannister is to pull the vapors out of the gas tank, and put them into the throttle body, which get sucked into the air manifold, so it will create a vacumn in the fuel tank. Some newer cars even have a SES light that comes on if the fuel cap isn't put on properly, beacuse it creates an air leak, prevent a vacumn from being in the tank, and thus decreasing gas mileage. You may notice that when you take the fuel cap off, it hisses. If not, the line that goes up to the canister may possibly be leaking, plugged, not correctly connected, or the solinoid might be dead. The canister itself may even be cracked. You said that there was no gas smell, so I think you can rule out a tank leak. Just in case, I would check for moist spots on the fuel tank.
That is all I can think of. Hope this helps.