I have a 91' camaro RS+ with the V6. Sometimes when I fill my gas tank, after I have driven the car a few miles and park it, the gas will spew out past the filler cap. This happens rarely, but just on hot days when I have driven the car and the engine is warm.
The problem has only happened since my original fuel pump failed and was replaced a few years ago.
On a related note, ever since my fuel pump was replaced (I had it replaced 3 times in 24 months) I get a strong smell of gas when I fill up. My gas tank almost never goes below half full.
The autoshop tells me I have 2 bad fuel injectors and raw gas is being dumped into the catalytic converter. But sometimes the smell of gas is very strong from the rear of the car even when the engine is stopped.