Strong odor of gas coming from the vents and just outside the drivers side. 2003 Pontiac Bonneville.

irish

how can I fix it

Mr_Shiftright

Lots of possibilities, and this will require your close inspection. Obvious causes are fuel leaks at the injector or in the fuel rail but you could also be having problems with the EVAP purge valve or vent valve, or any of the many hoses linked to the EVAP system.

imidazol97

I believe the fuel filter is right below the passenger door on the driver side. Have you have anything done to the car like servicing that filter when it was in the shop? Might be leaking at the snap connection there. Or it could be rusted through the metal case of metal line in that area.

But you said the smell is coming in the vents. I assume that means the air intake for the heater vent.
There is an o-ring connector on the fuel line behind the top of the injector line. The flexible fuel line connects to a snap on connector and that o-ring could seep if it had been disturbed such as someone working over it to reach the sparkplugs behind it. Often wiggling the connector would stop the slight seep of fuel there. This would leak without the engine running just with the key ON which pressurizes the fuel line.

This connector was toward the driver side of the engine.

Then there are all the places that Mr Shiftright mentioned.

A fuel smell needs to be diagnosed and repaired quickly because it is dangerous.