When the tank is past 3/4 full there is a gas smell. Also when take off the gas cap there is loud sucking sound from pressurized air. Also after driving for a short distance the engine gets fluded. Do you think it can be my Gas pump? Also how often do you replace your gas filter?

90 civic si with 135km

 

im assuming you mean 135,000 which is in the high 80k mile mark, you should do a tune up every 90k miles or 145000km