Petrol tank vent pipes

[Andrew S]

I am just replacing my venting pipes for the petrol tank and would appreciate confirmation from anyone who can confirm which pipe comes out of what hole?

Am I correct in thinking that the vent pipe that come out of the outlet side of the breather filter goes out the bottom of the boot floor and the other pipe which comes off the back of the petrol filling pipe goes out of the boot floor higher up at 90 degrees? The payout below shows both pipe grommets as being on the boot floor.

Any photos would be great if anyone has their tank out

Thanks for your help
Andrew

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[ampotter]

Hi Andrew

I recently removed my petrol tank to give it and the boot floor a coat of hammerite and I was also puzzled as to the layout of the breather filter (mine was missing). As you stated, the breather from the top of the filler neck connects to the filter and a pipe from the filter passes through the boot floor via a grommet under the fuel tank (as per diag). However, the diagram is confusining as it shows a second pipe passing through a grommet but not connected to anything. I have found no other breather outlet and therefore can only assume that this my have been fitted to a very early model from which the diagram probably is based upon.

Andrew

[Andrew S]

Hi Andrew

The second pipe that you see on its own connects to the under side of the petrol filler cap. You cant see it unless you look underneath and its very tight. This pipe is for over filling the tank and any kick back or over filling will go down this tube. Th reason why there is a difference between the tubes is that one of them comes out of the bottom of the boot floor and has a angled cut on it that points in a certain direction as when you you are driving along, the air flow causes a sucking action and therefore all fumes are taken away as you drive from the breather.

Being that both tubes connect to the filler cap, they are both exposed to fuel vapours, one having a filter and the other not. Why have a filter on one of them????? Is it a flame trap or something?

Should be getting new tuning Wednesday and wanting to fit it all so that I can get the tank in, but as you say, the diagram is confusing

Andrew

[dasadrew]

Not sure if these help, but here goes...

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[Andrew S]

Thanks for doing that Drew. Unfortunately, it doesn't show the pipes. It shows one in the second image to the right of the big filler pipe. The thin clear tube and this one of them where I don't know if it goes out the bottom of the boot floor or out of the back of the floor.

Thanks again
Andrew

[dasadrew]

maybe this one then?

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[ampotter]

Andrew

I will have to have a good root around the filler from inside the boot to find where the second pipe fits. Stags are one continuous learning curve!

Andrew

[Andrew S]

Thanks Drew, we are almost there. Using your last image, I have marked where the pipes exit the boot floor. The pipe that is being shown on the right going through the grommet out of the back of the floor, where is this coming from? Doe sit come from the filter on the tank breather or directly from underneath the petrol cap?

Thanks for your help
Andrew

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[V Mad]

Hi Andrew

Being that both tubes connect to the filler cap, they are both exposed to fuel vapours, one having a filter and the other not. Why have a filter on one of them????? Is it a flame trap or something?
Andrew

I think the filter is a flame trap as this tube is the breather for the tank; the other pipe does not need a flame trap because it is blocked off when the filler cap is closed. Does that make sense?

[Andrew S]

Thanks Chris, that makes sense. So, do you know if the flame trap one goes down the hole where I have arrowed on the left or out the back of the boot floor where Drew's pipe is shown disappearing through a grommet?

Cheers

Andrew

[V Mad]

No, but my guess is that the drain hose goes to the nearest hole in the floor; the breather goes to the other one.

[Andrew S]

Good point Chris

Cheers
Andrew

[dasadrew]

Just been out in the garage trying to piece the bits together. Am still a bit handicapped by the hand-in-a-splint trick, so can't lift fuel tanks and boot lids!

The line with the flame trap (?) filter has two distinct ends which are formed to push over a 90° rubber elbow. You can see on the close up pic that the exit spout next to the lower elbow is a very dark golden-brown colour. I found the upper elbow still attached to the filler cap assembly. Looking at the underfloor photos the lower brown spout can clearly be seen exiting vertically downwards

The straighter tube which disappears forward on my earlier pic is also shown in one of my photos. For abovementioned reasons I can't see where the top of this tube connects to but you can see where this exits on the underfloor photo too.

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[Andrew S]

Drew, this is great thanks and different to what i was thinking. The flame trap then goes through the bottom of the floor with the brown end and the fuel over fill goes out the back. Excellent

By the way, the other tube also attaches to the filler cap. If you turn it round you will see where it attaches, awkward to get to when fitted.

Thank you for doing this for me and hope the hand repairs quickly.

Cheers
Andrew