Sound advice needed / high pitched mystery sound

[Mernest]

I am desperate for some advice.

I have a recurring Evap Code/Check engine light issue. So far I have had it smoke tested, have changed the gas cap, purge valve, charcoal canister, and fuel pump.

Here is the frustrating part, which I am not sure is related. From the right rear where the evap stuff is housed, I get a high pitched whistle sound, like a balloon deflating. It is not constant. Sometimes it does not happen, other days it's non stop. Of course, the mechanic can never seem to hear it while driving it, despite it being very loud at times. Also, about a minute after I shut the truck there is a loud low pitched groan from the same spot.

Some other info: The gas cap pops off like a champagne bottle when I fill the tank. It spits the gas out never stopping on its own while fueling, and sometimes it doesn't want to take gas. I've gotten Evap Leak Detected Very small/Very Large, and misfire codes.

Here is a link for the sound
https://drive.google.com/file/d/1kHa69-rqzWcdB5tVj5hUzHh5jyI_-nj2/view?usp=drive_link

 

[Mall'er]

Year?
Engine?
Codes?

Your link requires a login request.

 

[Mernest]

2006 tj 6 speed manual 6 cylinder.
Codes are regularly 452, 455, and only once or twice 300

The truck drives great despite this issue.

 

[DuckNut]

It spits the gas out never stopping on its own while fueling, and sometimes it doesn't want to take gas

This is because the check valve inside the tank is sticking in the closed position.

You need to drop the tank, pull out the valve, sand the ears down, and reinstall. Lots of info around on how to do it. YouTube will have you certified in no time.

 

[Mernest]

Thank you so so much. While the gas issue is annoying, it’s the least of my worries. The high pitched noise and unfixable evap leak codes are my main concern.

Any other tips?

Thanks again.