MK5 Fuel Tank in a Vaccum - Breathing valve?

[trashpanda]

Hey everyone,

I've been experiencing a strange issue with my MK5 Ford Transit's fuel tank lately. The tank seems to get sucked into a vacuum and when the cap is released it expands back to its normal size. This problem has become so severe that my fuel gauge doesn't accurately show fuel consumption unless I release the cap.

I'm wondering if anyone else has encountered this issue or has any insights into what might be causing it. What should I be looking for in the first place to diagnose and fix this problem?

Any advice or suggestions would be greatly appreciated!

Thanks,

[trashpanda]

sorry, coulnd't find the edit button.
I forgot to mention my fuel cap isn't original, could this be the cause? is the breathing valve in the original fuel cap?

[Chug]

There is a breather valve/pipe on the side of the fuel tank.

[dumper]

Looking at the Haynes manual it has a vent pipe have a look around the tank and filler neck .

[trashpanda]

Looking at the Haynes manual it has a vent pipe have a look around the tank and filler neck .

Could i ask you to show me that part of haynes please?
i also forgot to mention it's a Cab chassis

[Chug]

https://www.catcar.info/ford/?lang=en&l ... IrMA%3D%3D

[trashpanda]

Thank you, number 14 should be the valve right?
i'll take a look at what's wrong

[dumper]

Nice one Chug tried putting a photo up couldn’t get it on and in the manual it didn’t show a pickup.