raw gas smell in cab

[Bugsiegel]

when the climate control is on the smell of raw gas is entering the cab. it's to the point now that even at a stop light it starts to build up.
No obvious visual leaks around the fuel rails. Not sure where to look next.
2007 v8. No codes and no idling or running issues noticed. Can kind of smell it under the hood on the drivers side but can't pinpoint it. Don't smell it anywhere else outside of the truck.
Thanks in advance.

 

[swshawaii]

Finding fuel vapor leaks may be difficult without trouble codes. EVAP system test maybe?

http://www.underhoodservice.com/up-in-vapor/

 

[Todd Z]

How long ago did you change the spark plugs ??? Common issue with the 4.6 V8 is the plugs are loose.... believe it or not.

 

[EddieS'04]

Also the fuel system and fuel rails are under pressure. The fuel evaporates imediatly. You wont see evidence of a small leak. It takes a special electronic sensor to find it.

 

[Bugsiegel]

Todd,
You nailed it. Cylinder 5 plug was loose which makes sense now because it only smelled when the climate control was on and that's only on when the truck is running. We couldn't smell it when the truck was off and the hood was open. luckily it was the first one I checked. I proceeded to check 6 and 7 as well. 8's a challenge on this truck. I didn't check any more.
I first was under the truck to check the connections on the fuel filter which I changed a few months ago. What a rusty mess the underside of this truck is. Mechanically it looks like it can make it to 300k and I was hoping to drive it that long ( currently 180K) but the body is just rusting all over the place. Cab corners are now both in bad shape. The 2004 Toyota looks so much better underneath. Both in the same environments.
Thanks to all the responses. Check your plugs.

 

[Todd Z]

Your very welcome.... Glad to help !! Sadly it seems these are rusting out ....... Ford doesent build them like they used to.... planned obsolescence in my eyes