Fuel tank vent?

[FarmyardPants]

Hi chaps. Whenever I fuel up the cerb there's a fair amount of vacuum in the tank when I remove the cap. How is the tank meant to be vented? I don't want my fuel pump fighting a vacuum. Any ideas? Does anyone know of a replacement cap with integral vent? Cheers all.

[peteA]

FarmyardPants said:

Hi chaps. Whenever I fuel up the cerb there's a fair amount of vacuum in the tank when I remove the cap. How is the tank meant to be vented? I don't want my fuel pump fighting a vacuum. Any ideas? Does anyone know of a replacement cap with integral vent? Cheers all.

I was under the impression it vented into a vessel (containing a carbon filter if my memory is working as it should) in the near side rear wheelarch behind the fuel filter...at least thats where it is on mine...

You maybe need to check the hoses and the filter...might be a bit of a bugger to get to and remove...

Think its quite normal to have some vacuum mind...maybe others will comment?

[FarmyardPants]

Cheers. I've read about the carbon can (or carbon can't in my case , maybe it's blocked up)

Sometimes when the fuel pump primes, there's a thud from the tank as it collapses a bit and changes shape, so I definitely have a problem getting air in to replace the fuel pumped out. A one way valve in the cap would fix it..

[dean_ratpac]

i've been told the carbon canister is on a one way valve. hence the wooosh is air going in - not out as i had oringally thought. I've had a separate fuel breather and pipe installed. this was when my tank had hairline fractures (3 in total) the carbon canistor seemed to be working - but they couldn't find out why it was not equalising.

the carbon canistor pipe run all the way to the front wing - not sure which side. but having it disnconted has stopped the fumes 100%.

my new one sits under the rear N/S arch. TVR went this route with new emissions laws or something? it ties into the ECU too apparently.

[FarmyardPants]

dean_ratpac said:

i've been told the carbon canister is on a one way valve. hence the wooosh is air going in - not out as i had oringally thought.

Ok so the cc filters petrol fumes going out, which makes sense, I'm thinking of intake (maybe vent is the wrong word)