mcerbm Posted July 10, 2014 Share Posted July 10, 2014 I have experienced the left hander fuel deposit problem from my caterham on track days and have decided to fit the one way valve so that this does not happen again. I was about to fit it tonight but after over filling my car last night at the petrol station I could see fuel was leaking out from somewhere around the top of the fuel tank around about where the neck filler was. On further investigation tonight after lifting the honeycomb floor I can see that I have a fuel tank breather hose and a neck filler breather hose. I had a quick look on caterham parts website and couldn't see another fuel tank with the boss where my breather hose is fitted. see picture here I only have 1 x one way valve so i'm wondering if I have fuel leaking out of the fuel tank breather hose or the neck filler hose or both? I'm guessing most people have problems with the neck filler breather? I guess I don't need both breather hoses. I was thinking of blanking off the fuel tank hose and fitting the one way valve to the neck filler hose. seem sensible? The fuel tank is off a superlight R year 2000 Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 10, 2014 Share Posted July 10, 2014 While the floor is out ...... have a look at the sender gasket ... it will be crumbling and is only a couple of Pounds. Link to comment Share on other sites More sharing options...
chris956 Posted July 10, 2014 Share Posted July 10, 2014 I`ve had this recently so did a bit of digging and fiddling. Looking at your picture , to me it looks like there has been petrol sitting ontop of the tank around the sender unit opposite to the fuel breather and filler neck. I had the same as you on left handers and I couldnt find any obvious problems. My theory is that once the car has been thrown round a bot the petrol expands in the tank and that expansion has nowhere to go as the one way valve fitted to the breather only allows air into the tank not out. So , therefore it must be seeping through various cracks in the rubber or through bad joints under pressure. It costs peanuts to replace all the rubbers which is what I intend to do for piece of mind. No need to get the bespoke Caterham parts ,any decent motor factor will carry fuel resistant pipes & rubbers. I did suggest my mechanic sits in the boot whilst I blast it round and round trying to get the petrol to leak out but he wasnt to sure about that !! Link to comment Share on other sites More sharing options...
mcerbm Posted July 10, 2014 Author Share Posted July 10, 2014 I don't have a one way valve fitted to either at the moment. I only have 1 x one way valve. I'm away on a trackday holiday on saturday so I will need to fit the one way valve to one of them and clamp the other one. I was going to fit the one way valve to the neck breather as that seems to be the common cause. I didn't even know there was a breather on the tank until I over filled it! Link to comment Share on other sites More sharing options...
chris956 Posted July 10, 2014 Share Posted July 10, 2014 Well you could do what I did and zip tie a plastic lemonade bottle underneath and run the end of the breather into it...... That will immediately tell you if it leaking out through that. Still think it looks like the petrol has pooled on top of the tank near the sender unit though Link to comment Share on other sites More sharing options...
Ian B Posted July 11, 2014 Share Posted July 11, 2014 See also workshop notice PDF in my dropbox here Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 11, 2014 Share Posted July 11, 2014 From that era ... did a breather somewhere in the system go to a charcoal canister ? Just recalling stuff I read a while ago ? The position of that spigot isn't far from where the fuel return (to tank) is located on my 2002 car. Edited by - SM25T on 11 Jul 2014 08:49:41 Link to comment Share on other sites More sharing options...
BBL Posted August 16, 2018 Share Posted August 16, 2018 I'm seeking information on the fuel tank breather inlet, please.Long ago, I remember reading a post (or multiple posts?) describing, with photos, a fuel breather modification/enhancement with a "down/up/down" hose configuration and a one-way valve in-line. I have found a few old threads providing some insight, but nothing comprehensive, and nothing with photos (except pre-BC migration links, which are all inactive now). One post references Workshop Notice 371, a.k.a. WS 371. Can anyone provide some insight, please? Link to comment Share on other sites More sharing options...
Strangely Posted August 16, 2018 Share Posted August 16, 2018 Workshop Notice 371 -- Injection Fuel Tank Breather Link to comment Share on other sites More sharing options...
BBL Posted August 16, 2018 Share Posted August 16, 2018 That's the one. Thank you, sir! Strangely, I'm happy. :) Link to comment Share on other sites More sharing options...
anthonym Posted August 18, 2018 Share Posted August 18, 2018 @SM25 he's talking about the same tank I have (My year 2000 K series), the one you helped me fit with the new filler cap and filler hose and "updated" one-way-valve breather (off the filler) and we blanked off the tank breather after asking Caterham Cars because the second breather is no longer included in the filler arrangement. Link to comment Share on other sites More sharing options...
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