Ok. I guess I missed your lat posting of 12:34 p.m. As I suspected, most likely it is the canister, but I would also suspect the valve,which opens and closes to allow tank gases to exit the tank and into the canister. Either one would cause the condition you described, however, there may be other conditions/components. Have a parts store use a scanner to read for any codes. The codes will tell you exactly the problem location. By the way, the canister is located next to the gas tank in some vehicles. Some are easy to get to, some are not. The valve is attached to the canister.