Chevrolet Repair: Smelling gas, chevy cavalier, loud pop

Question
Hi.
I have a 1996 Chevy Cavalier and when driving the car you can smell gas in the car. Very strong smell too.
I tried looking under the hood and i smelled some gas somewhat on the right side near the front window but not like it is inside the car.
Also, when driving there is a loud pop in the trunk kind of like a rock hitting the car.
Someone suggested that the gas tank is building up pressure and to put a slit in the gas cap to releave the pressure. Would this be safe? I bought the car used about a 1 1/2 months ago.
I noticed the gas smell a little off and on a few weeks ago and then the other night it was so strong I almost could't stay in the car.
Thanks for your time.
Michelle

Answer
Hi Michelle,
There are several things I can think of, but the most important is get that problem found soon.
It could have the wrong gas cap.
The vapor canister system may be plugged, disconnected, or just have a malfunction.
But that may be a problem you should have someone check for you. if the fumes are that bad, there is an explosion hazzard.
Van