Weird heat waves emitting from fuel door?

[4rociousrunner]

So today I was out wheeling on a moderate trail (larger rocks, dried out divots, mud, etc.) when I noticed something weird. About halfway through, I started smelling gasoline fumes, especially when my A/C was on. We stopped to check for leaks outside the vehicle and in the engine bay but found nothing. We continued and stopped for a break. After starting the truck up again, I noticed the heat waves (clear, ripple like) emitting from the fuel door. They disappeared after turning off the engine and reappeared after starting again. I left it on and opened the fuel cap to which I heard a weird gurgling sound from the gas tank and a little bit of white/grey smoke or vapor....any clue what this is???? Maybe air bubbles being formed due to the constant rocking of the vehicle on the trail?

 

[4Reak Show]

Yeah it's fine. My 2nd gen does the same thing. Shaking up the tank makes for more bubbles and more vapor and more pressure. With the engine running, the EVAP system purges the vapors so that's why it slowed down with engine runbing. Most gas caps will vent off after a certain pressure is reached. Also, changes in elevation will increase overall pressure and cause fuel cap venting. Don't smoke around the fumes and you'll be fine. But still carry a fire extinguisher. For piece of mind if nothing else

 

[TheUltimateBohab]

What 4reak show said sounds way more likely but I have seen something like that on only Chevys never even heard of it on anything else but on those garbage cars the EVAP or pressure release system would plug up from driving on fieldroads and cause it to build pressure inside the gas tank to the point where you couldn't fill it up and it would actually spit gas back out of the fill tube. I'm sure your problem is different it's just the only time I've ever seen anything similar....

 

[4rociousrunner]

Ok that’s what I figured...we were also on a ridge which was increasing in elevation pretty drastically so that might be the reason. Plus the smell and heat waves went away once we got back on the road/ back to a lower elevation. ����