when i put gas in the car i smell it for a while

Hello, this may be normal. But, it would be worth while to check your fuel system for any kind of vapor leaks. A qualified technician with evaporative emissions equipment can "smoke test" your system to see if your fuel filler neck or any other component has a vapor leak. Typically, when a leak is detected by the vehicle, the "check engine" warning indicator will come on, but proactive testing is not a bad idea anyway.