This could be a major issue for me as i am off on a road trip tomorrow. changed my fuel filler cap for a new shiny one that is meant to be breathable. click took the car out for a test drive today and thought i better fill the tank in preparation for tomorrow. as i undid the cap there was so much pressure it blew the cap off. obviously the tank is allowed to breath in to stop a vacuum but it is not letting the pressure build up in the tank out.

should i leave it as is and hope all is ok. put a very small pin prick in the top of the filler hose at the highest point to let the excess pressure out or modify the cap.

the clock is ticking and i dont have time to get a new cap (old one went out in the bin :-( ) what should i do?

Remove the breather valve and just loop a pipe up and down untill you can get a two way valve.

Another option would be to drill a small hole in the fuel filler tube just below the cap.

Phil

[Edited on 26-4-11 by Hellfire]

I've got the same cap and the same problem. I have done 300 mile now with no major issues other than I think I may be over pressurising my 40's. But the way it makes me drive it its not that long before I have to take the cap off to re fill. Its on my list to do

RD

[Edited on 26/4/11 by rallyingden]

Assuming you have a 2" rubber hose onto the underside of the filler,

I think I would just loosen the hose (jubilee) clip, or remove it completely
and take it with you.

You could then get the proper vent valve without messing anything up.

Cheers,
Paul G