I bought a 2000 Accent for my daughter because for the same money I could have purchased a 1992 Civic. Hope I did not make a mistake. After replacing the mass air flow sensor, the air filter, the fuel filter and the spark plugs the car funs fine. My problem is that after you turn off the engine you can hear pressure bleeding out of the I think is the fuel system and then a small bang in the gas tank. If I remove the gas cap while the car is runnng the check engine light comes on but when you turn of the car there is no bang from the gas tank. The Hyundai dealer just says to ignore the problem since he has no idea what is causing the problem. As I said before the car runs fine but I would like to know what is happening. I replaced the gas cap but this had no effect. Any ideas?