2005 Chevrolet Monte Carlo - Smelly gas cap?

Live in Phoenix.In hot weather,I notice a quite strong gas odor around the back of my car.No gas leak.No check engine light.Could it be coming from the gas cap?I’m seeing differing answers as to whether or not modern gas caps are supposed to vent fumes.

Modern systems require the cap to be sealed…non-vented.


+1 or @oldnotdeadyet on that answer.

You did not even attempt to describe the smell sooo, how are we to even guess what it might be? You might have hit a skunk.

A little related, our 7hp motor 3 gal tank at the lake went up missing. New gas can. It vents in but not out, so first sunny day the engine was spewing gas due to the pressure from sun heating up the tank and yes the needle valves are good. Solution, leave the cap loose, I am sure vapors from the tank are better than spewing fresh gas into the lake.

The odor is from fumes vented from the vapor canister. There are a lot of fuel odor complaints during the summer months, more often with the older vehicles that circulate the hot gasoline through the fuel rail then back to the tank. After an hour of city driving in 110 degree weather the gasoline in the tank is hot and the vapors overcome the capacity of the vapor canister.