OK i was driving today on 3/4 tank of gas....so next thing i started to smell gas....i bounced out the car and checked the gas cap. i see that gas was coming from the cap. so i opened it to tightened it all the way but the gas started pouring out... that was weird. so i just closed it back up and tightened it all the was hard. do you guys think that the system in my car is causing the gas to come out? i have 4 15's in the trunk. if thats not the case then i do no know what the problem is.

 

Something is definitely wrong with the venting system. Somehow your getting pressure in there and when you open the cap the air rushing in forces the gas out. Try getting a new gas cap,

 

check the charcoal canister. it lets air in the tank to compensate for the loss of gas while driving.