Fuel tank breather

[EvoHP]

Hey Guys, I noticed on my Evo x that when removing the filler cap I can hear it sucking in air.(of course only after using a tank of fuel between openings).

It can't be by design surely? I think my filler cap breather is not breathing. Any ideas?

 

[evogeof]

ive come across this a few times should be ok

 

[fq-craigus]

my ep3 used to do this all time and it never missed a beat. imo nothing to worry about matey

 

[Steve220]

Its only because you've used fuel and its creating lower pressure in the tank. Its perfectly normal.

 

[EvoHP]

Thanks for the info , I get the physics of it. I have had many cars and te lat time I had this problem it was on a carburated model and the mechanical fuel pump couldn't overcome the vacuum and would eventually cut out.

I guess the vacuum keeps fumes from escaping.

Thanks again!