Fuel tank vacuum?

[pirateprentice]

When I remove my fuel filler cap there is a woosh of air - as if the tank is forming a partial vacuum as the fuel is drained.
Is this completely normal? I don't remember it on my previous cars.

 

[scm]

I get that, too, I assumed it was just releasing the pressure in the tank. More noticeable after a long drive when you've used a lot of fuel in a single run.

 

[Andyp123]

Normal

 

[cj10jeeper]

It's to reduce vapour emissions through fuel evaporation. Completely normal on cars these days as they vent through controlled mechanisms.
Noticeable of course when you open the fuel cap. One of the reasons cars can fail MOT's for perished or split fuel cap seals

 

[pirateprentice]

Thanks, good to know.