Pressure in fuel tank... Vacuum? - Saxperience

DavidKent · 29th May 2008, 22:01

As above..

Basically every time i take my fuel cap off, there's like pressure, or it takes air in, and its like there's a bit of a vacuum thing going on inside the tank - Underneath the car the tank looks sucked in a bit if that makes sense.

Should there be a breather or something?
Seems a bit weird to me, And i'm sure it should take more than £35 from empty, almost like the tank is permanently sucked in!

Any help would be good.
Thanks

DavidKent · 31st May 2008, 17:58

Any suggestions on this?
Drove the car to work today, and when i got home i could hear a hissing noise.
I opened the fuel cap, released the pressure, and the hissing went.

Could it be because I don't have the fuel cap trim on there and its taking air in? Silly as it sounds.

Also looks like the bottom of the tank has risen a bit - almost like its been sucked in...

Cheers

123-samsung123 · 31st May 2008, 18:06

Sounds like youve got a blocked breather in the tank vent, look around the filler neck, the breather hole sometimes there, is it difficult to fill with fuel??

smittytom · 31st May 2008, 18:06

Have a look on this mate dont know if its anyhelp.
http://forums.preloved.co.uk/fuseact.../b9dce284.html
about 1/4 down the page it got something about a tank breather??
Dont know if its any good just thought i would share

EDIT: I was beaten

stevo67 · 31st May 2008, 18:16

On some cars their is a vent pipe I would jack the car up & check the pipes in particular things like is the vent blocked any splits in the pipes had this problem in an old Metro.This what the Haynes book says:If a hand operated pump is available ,disconnect the manifold vacuum pipe from the port at the top of the fuel pressure regulator-this will cause any residual pressure to be released in the fuel supply line ,via the fuel return line.Pace a rag under the union to be disconnected plus a container underneath,once the pressure is released re-connect up.

Essay over.

Steve.

DavidKent · 1st June 2008, 13:43

Thanks guys - Only real thinkg it could be is the breather then..

Any idea where it actually is?
Don't want to spend 3 years looking for something that i don't even know what it looks like!
Cheers

stevo67 · 2nd June 2008, 16:15

Right i`ve had a look in the Haynes book which is crap the vent pipe is in the filler neck,the breather hoses are joined to the tank in various places with quick release fittings.Sorry thats all the book says.

Steve.

DavidKent · 2nd June 2008, 18:04

Will have a look on the next dry day.
Cheers mate.