Is your engine light on? Have you been told it probably indicates a vapor leak?
My very good garage mechanic told me the last time I took my auto in for an oil change that the engine light on meant s possible vapor leak...which would have to be fixed before my next emissions control check. My state requires this. He said it involves dropping the gas tank and inspecting the hoses and whatnot. Seemed reasonable to me...Estimate wasn't cheap. So I told my handyman next door neighbor who owns every tool known to man. He asked if I had checked the gas cap. I had not. He came over the next day and proceeded to wipe down the little rubber gasket in the gas cap. Then he put a small amount of white mechanics grease around the gasket. I put the cap back on the tank, turned on the auto, and the engine light was gone. It has been three weeks and it is still off. I bought him a bag of caramels.