chris956 Posted June 11, 2014 Share Posted June 11, 2014 Hi all , started to get a smell of petrol last couple of fill ups and have started to investigate today..... On inspection the rear off side wheel arch shows signs of leakage on the trailing edge. Just above this I found the end of the breather pipe. Hold that thought. I then took out the boot floor to see small signs of petrol residue ( could be vapour ) around the bottom of both rubbers , the fuel filler and the overflow. On inspection both rubbers are integral with no splits , holes or tears. This leads me to think that the breather pipe may be letting petrol out of it. Now here is the question .... Having got hold of the breather pipe and blowing down the end of it, I can hear air escaping out of the fuel filler cap. Now when I try to suck and replicate the petrol coming out, the one way valve halfway down the pipe shuts and stops me mid flow which leads to the question : Should the breather pipe be allowed to let air into or out of the petrol tank ? If it is the former - how is the petrol leaking out ??? Link to comment Share on other sites More sharing options...
Myles Posted June 11, 2014 Share Posted June 11, 2014 If the breather didn't exist, the fuel pump would sucky-sucky until it could sucky-sucky no more (like trying to drink wine from a bottle without a breath). So, the breather should let air in (to prevent a vacuum) - but not let fuel out (e.g. When you corner left, hard - or roll the car!) Link to comment Share on other sites More sharing options...
chris956 Posted June 11, 2014 Author Share Posted June 11, 2014 Quoting Myles: If the breather didn't exist, the fuel pump would sucky-sucky until it could sucky-sucky no more (like trying to drink wine from a bottle without a breath). So, the breather should let air in (to prevent a vacuum) - but not let fuel out (e.g. When you corner left, hard - or roll the car!) Thats makes perfect sense and the conclusion I came too when I took myself into the dunce corner for 5 minutes I have re seated the rubbers and as a test, run the end of the breather into a seethrough water bottle so I can check on it next time. Link to comment Share on other sites More sharing options...
Ian B Posted June 11, 2014 Share Posted June 11, 2014 Chris, The fuel breather pipe mod is detailed in a tech note from Caterham. If you want to take a look there's a copy of it in my dropbox here Link to comment Share on other sites More sharing options...
Ian B Posted June 11, 2014 Share Posted June 11, 2014 although it sounds like yours is present and working the right way round Link to comment Share on other sites More sharing options...
prangerman Posted June 11, 2014 Share Posted June 11, 2014 Chris I had a similar problem a few years ago on my S3. Lifting the breather tube a few cm and securing it cured the problem. Peter Link to comment Share on other sites More sharing options...
chris956 Posted June 11, 2014 Author Share Posted June 11, 2014 Quoting Ian B: Chris, The fuel breather pipe mod is detailed in a tech note from Caterham. If you want to take a look there's a copy of it in my dropbox here Cheers Ian .. I had a look and my breather does a similar route although the "double back" is not as extreme and I presume that is now why a one way valve is fitted. Quoting prangerman: Chris I had a similar problem a few years ago on my S3. Lifting the breather tube a few cm and securing it cured the problem. Peter Yes , cheers Pete. I have reassembled with the end in a half litre bottle so it will be easy to check if it is coming out of the breather or by passing the rubber tubes for refuelling or overflow. Watch this space 😬 Link to comment Share on other sites More sharing options...
chris956 Posted June 13, 2014 Author Share Posted June 13, 2014 Brimmed it yesterday and had an "exciting" drive to and from Brands. No sign of petrol from the breather in the bottle and no sign of petrol leaking past the rubbers Perhaps it was just fitted together badly in the 1st place. Hey ho , another 5 minute job jobbed Link to comment Share on other sites More sharing options...
Piers Rendell Posted June 14, 2014 Share Posted June 14, 2014 Chris - I had a similar problem of petrol vapor when filling up, but the rubber gasket for the sender was the issue. It seems that lead free petrol has a bad effect on the rubber, which causes it to harden and crack. It is worth having a gasket as a spare in your garage and replacing it every two years or so. My gasket was falling to bits when I replaced it. Piers R300KWK Link to comment Share on other sites More sharing options...
RS2000 Posted June 14, 2014 Share Posted June 14, 2014 Something also worth a check is the main filler hose itself - it can look ok, but take a careful look as it can hold hidden splits like this picture from mine Link to comment Share on other sites More sharing options...
7 wonders of the world Posted June 14, 2014 Share Posted June 14, 2014 If it made from rubber and supplied by CC it's general very poor quality, the sender and pump seals on mine both failed in under 6 months from new both swelled to the point fuel p155ed out. Made my own seals from fuel resistant material and used a decent sealer and never had an issue again. Link to comment Share on other sites More sharing options...
Grim Reaper Posted June 14, 2014 Share Posted June 14, 2014 I believe the filler rubber hose is off the Rover 100/Metro Link to comment Share on other sites More sharing options...
Graham Perry Posted June 14, 2014 Share Posted June 14, 2014 As an aside, take the offside rear wheel off and check the pipes around the fuel pump as these are known to perish after a surprisingly short time. A leak from those would also show fuel residue in that area. The large circular mount for the pump have been known to occasionally leak as well Link to comment Share on other sites More sharing options...
chris956 Posted June 15, 2014 Author Share Posted June 15, 2014 Wilco roger Link to comment Share on other sites More sharing options...
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