When I fill my car up with gas, I have a few problems. For one, there is a leak somewhere between the gas door and the tank. Is there any place I should look inparticular. Also, I have a locking gas cap that is missing the rubber gaskets and it doesn't lock anymore. Therefore it has a real loose fit. Could this cause a loss in gas. Also, I think the gas gauge is going. I will drive the car and it will read half a tank. Then I stop the car and start it up about half an hour later and it reads 1/8 of a tank. Plus, the pump cuts off before the tank is full. I have never seen my gauge read full. Any enlightenment on my problems would be awesome.