Fuel tank breather and vent tubes

[Grubbster]

Just out of interest, does anyone know what what the various pipes are for around the filler neck on a 2001 car? Reason for asking is just that I noticed my 2003 car is different to a friends 2001 car and I wondered why?

 

On my car, if you take the cover off and look at the filler neck, there is a think pipe that runs from the filler neck straight into the tank - I assume this is for venting while putting fuel in. There is also a long, think pipe that forms a loop on the side of the tank, I assume this is for breathing - to allow the fuel to get out of the tank!

 

Now then, on the 2001 car there is another pipe - it comes off the filler neck alongside the breather, then goes through the floor (by the main fill pipe) and heads left on top of the fuel tank. Not sure if it ever joins anything else. Can anyone tell me what this is for, or where it goes?

 

Roadsport build photo's here

Le Mans 2004 photo's here

 

[F355GTS]

2001 car small pipe is a breahter to the top of the tank, the small one in the neck on yours was originally there as an overflow I think

 

I thought all 7 tanks have the breather on top of the tank?, perhaps yours is buried under the floor?

 

Mark

[Grubbster]

*confused*Confused now! Mine has a big pipe the petrol goes in, attached to it and going straight into the tank is a smaller pipe (on the left side), and then on the right side an even smaller tube with a long hose that goes down and loops up and down the side of the fuel tank.

 

On the 2001 car it is similar but for an additional pipe on the right hand side that goes through the boot floor and along the top of the fuel tank (possibly to a vent on the tank??) I just wondered why this extra one was there and why it is no longer deemed to be needed.

[Myles]

AFAIK (having implemented the non-return valve on the breather...)

 

i) Big'un lets the fuel in

ii) Smaller one lets the tank vent (during filling)

iii) Teeny-weeny mystery one is an overflow

 

The overflow (as standard on an 01 car, at least) vents to the atmosphere - and on hard LH corners you will see it *p!ssing* fuel onto the road if the tank is above about 1/2 full. The mod is to fit a one-way valve into some extra piping on the overflow pipe - there are links to a .pdf file on BC (search TT).

 

 

 

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Alcester-Racing-Sevens.com

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[Grubbster]

Thanks Myles - I know about the valve mod - that is what we were looking at doing and hence spotted the difference between his set up and mine. I think I agree with your i), ii) and iii) - but what about iv)? It is this one that confuses me!

 

I assume then that there is:

 

i) Big'un lets the fuel in

ii) Smaller one lets the tank vent (during filling)

iii) Teeny-weeny mystery one is an overflow

iv) Another teeny-weeny one - maybe breather???

[Myles]

Fuel return pipe from the engine? I'm not quite sure where it goes on my 01 car...

 

Project Scope-Creep is live...

 

Alcester Racing 7's Equipe - 🙆🏻™

 

Alcester-Racing-Sevens.com

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[Ian B]

Just found this whilst searching what to do about my 2001 SV pissing fuel out from under the rear wheel arch on LH corners (especially on track) when over 1/2 full.

 

Mine doesn't have the one-way valve mod PDF here so I'll do that which will hopefully cure it.

 

For reference, this photo (taken looking down into boot) shows the filler neck pipe arrangement on my 2001 SV.

The top breather (bottom of the photo) spills fuel when cornering, and needs the loop and 1-way valve mod from the PDF above.

The small breather below it (on right in photo), I understand used to go to a breather port on top of older fuel tanks - on my factory built SV it is simply strapped to the top breather pipe, and has the 'loose' end simply taped over with what appears to be self-amalgamating tape.

 

 

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Ian - MI 5EVN - Slightly Vider SVelte model 😬 now repainted to match the Autocom headsets (and AA recovery truck 😳)

 

Edited by - Ian B on 26 Aug 2008 19:14:05

[Stationary M25 Traveller]

Yup - did that mod on mine about 6 months ago - no more needless waste of fuel all over the road ! *thumbup* Assume CC do this on new builds now ?

 

 

[Ian B]

I wouldn't necessarliy assume so 😔; the PDF notice is dated 2002, so after mine was built, but not yours?

 

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Ian - MI 5EVN - Slightly Vider SVelte model 😬 now repainted to match the Autocom headsets (and AA recovery truck 😳)

[Atinod]

Well, the large one on my 2007 car is to let rain water in during heavy rain storms, which contaminates the diesel in the tank, requiring the draining of the tank, new fuel filter etc etc.

 

 

But that's a Land Rover for you

[Stationary M25 Traveller]

Mine was registered on 8th October 2002, so long built by the time that Tech Bulletin was published !