As has been said before, it sounds like your fuel system is leaking under pressure when the engine is running. The smell of fuel is a dead giveaway.
Get it looked at asap, and if it was me i wouldn't be driving it unless absolutely necessary. I had a fuel injection hose split on a 2.0L Vauxhall Cavalier once, i drove it around for 2 days with the smell of fuel getting stronger and stronger. When i opened the bonnet (with the engine running) i spotted the split hose immediately, there was a fine mist of fuel (liquid/vapour) spraying everywhere. The entire engine compartment was wet and glistening, with fuel evaporating in clouds off the hot engine/manifold!
How it never went up i don't know.
