Hissing noise from fuel tank

Warmed the truck up in the drive way this morning....when I went out to leave I noticed a hissing sound coming from the fuel tank area. Almost sounded like a leaking tire hiss.....or noisy fluid flow through a line.

I made a few stops while running some errands, then left the truck running while hooking up a trailer....still making the noise.

Drove about 20 miles, got out to check it with the truck running....still making the sound.

Tried turning the truck on and off a few times and starts making it again every time when running and stops immediately after shutting it off.

Checked the gas cap and no difference after re-tightening.

Did some searching on the forum and found a few 2nd gen threads which mentioned it could be a purging... but nothing I read was real conclusive.

Any ideas? Anyone else experience this?

Thanks ahead guys.

 

Snake. yep definitely a snake

 

He's getting the noise wth the truck on scooter. So it's not the self leakage test. My guess would be your hearing the fuel pump or have a vacuum leak. Vacuum leak should throw a CEL though.

 

That was what I was thinking, surprised I'm not throwing a CEL if it's a vacuum leak.

Definitely never heard this one before.

Guess I will monitor it and take to the dealer if I doesn't go away.

 

Mine makes that hissing sound too. I assume it's the fuel pump

 

Fuel evaporation leakage check? Maybe it's confused.

 

HAAAAAAAAAAAAAAAAhaaaaaaaaaaaaaaaaaaHHHHHaaaaaaaaaaaaaaaaaaaaaaa

 

parked my truck at 11:30 am did not drive it again and at 8pm went into the garage and it was doing whatever it dies and making the noise. that just seems weird 8 hours later it runs self tests....

 

Mine had a noise very similar to what is mentioned a while back and it was constant for like 12 hours and then stopped and to this day never again. Dealer told me “it’s a normal characteristic of the truck” even though they weren’t able to duplicate the noise