YARIS 1.3 Vaccum from EVAP line

[mik36]

Gents

I had this strange issue in 1.3 petrol engine the evap line I can feel have a high pressure vacuum
When I open the tank cap I feel hissing noise feel pressure released
Is this normal
I was looking at the evap purge valve which has one line from fuel tank evap this line has got vaccum in it and when I removed the finder the rpm increases this line connected to black pipe in the valve there is grey one from this valve which i believe goes into engine


No codes.
When I remove my finger from evap line the rpm increases and LTFT jumped to 9
Any help to test cross check would be highly appreciated

[komichal]

Whenever I remove the tank cap I actually do not hear hissing. I hear clapping as there is negative pressure in the tank that sucks air from outside and I guess there is some protective shutter that that makes the clapping.

Driving Yaris 2007 hatchback with 2SZFE 1.3 engine. Bought it in 2012, always behaves like that, never threw a code, never had any problem with this.

[Compeer]

Gents

I had this strange issue in 1.3 petrol engine the evap line I can feel have a high pressure vacuum
When I open the tank cap I feel hissing noise feel pressure released
Is this normal
I was looking at the evap purge valve which has one line from fuel tank evap this line has got vaccum in it and when I removed the finder the rpm increases this line connected to black pipe in the valve there is grey one from this valve which i believe goes into engine


No codes.
When I remove my finger from evap line the rpm increases and LTFT jumped to 9
Any help to test cross check would be highly appreciated

Normal, all my toyotas hissed like theirs vacume in fuel tank when i get gas, current yaris does it too. never ran it without cap on to notice any change,

[zoidberg444]

Whenever I take the fuel cap off mine it always hisses as air rushes into the tank. I always assumed the EVAP system kept the tank under vacuum in order to draw petrol vapours from the tank into the intake to prevent them off gassing to atmosphere.