4Runner Heavy Fuel Smell/Gas venting help!!!

I know I posted this in the 2nd gen section, but this area sees way more traffic than t4r.org and 2nd gen Tacomas and 4th gen 4Runners are very similar. Just looking for some opinions.

I have a 2003 4Runner Limited V8 135k. For a while my wife has complained about a gas smell after driving for longer distances. I've duplicated it a few times but could never quite locate the source. I replaced the purge valve and gas cap as I know it's a common failure on all vehicles. Still does it. So this weekend we went camping and took our 4 bikes and pop-up trailer up the mountain to approx 8000ft and while backing the trailer into position I noticed gas fumes coming from the fuel door and the smell of gas was very obvious and nauseating.

So after my long story I guess my question is what seems to be the common evap system failures on these? Filler neck? Vapor canister? Canister close valve? My gas mileage is normal 14-16mpg and no fuel leaks noted on the driveway or gas tank (only transfer case leak noticed.....).

Has anyone ever experienced this same/similar issue?

 

Does the gas cap on it actually stay tightly locked? I know someone with an 04 4Runner and it's like the filler neck (not the gas cap, but the metal filler neck) wore out around 150k miles. No gas cap, not even the OEM ones will stay tight.

 

It seems too. I'm gonna get a factory one tomorrow and see if it's any better. If not, I'm thinking it might be the over-fill valve. If not that then filler neck it is.....Ugh.

 

Bad beans?