'89 W124 Wagon Smell of Gas

[LKNMAN]

High all, new to this list, so if I post wrong location please let me know. Now to the question...

During the last week I have begun smelling gas. It seems to be coming from the engine comparment, yet I can smell it at the rear of the car as well. I have made an inspection in the engine compartment, and under the car, with it running but did not see any apparent leaks. Even after shutting the engine off the smell remains strong for an hour or two. Driving donw the road I can pick up the smell from the air the heater brings in the passenger comparment, thus making me think it is coming from the engine compartment.

Looking for any suggestions on how to track down the culprit. Thanks

LKNMAN