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Author Topic: Fuel tank pressure / vacuum  (Read 667 times)

Offline Mekaniko

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Fuel tank pressure / vacuum
« on: July 30, 2021, 11:41:12 am »
Every time I refuel the fuel tank there is pressure or vacuum when opening the cap on the fuel tank and I can hear how the deposit is returning to its original form.

Also when opening the driver door I listen a kind of breath from the engine bay.
No fault codes, no MIL on

I’m thinking on the N80 valve and the charcoal canister but have not found any information regarding.

Thoughts?

Offline Pudding

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Re: Fuel tank pressure / vacuum
« Reply #1 on: July 30, 2021, 06:56:35 pm »
That is normal and a sign of a well sealed fuel system.  If the N80 was stuck open, or if there's a leak in the evap circuit lines/carbon can, you wouldn't get that whoosh noise when removing the petrol cap.




2007 ED30 | 2009 TDI 140

Offline Mekaniko

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Re: Fuel tank pressure / vacuum
« Reply #2 on: October 27, 2021, 01:02:58 pm »
TBH still worried with that as checked with another MK5 GTI from a friend and he does not have that pressure/vaccum


Offline Pudding

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Re: Fuel tank pressure / vacuum
« Reply #3 on: October 27, 2021, 02:01:26 pm »
If there is no fault code or MIL, don't worry about it.


2007 ED30 | 2009 TDI 140