Long range tank - breather line versus fill line

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Originally Posted by dom14

I'm wondering whether LRA has done a half hearted job on mine(some twenty five years ago).
There's no "vent to atmosphere" hole/filter/valve from the tank or the fill line/quick fill line plumbing.
Only valve is the black cylindrical one in the picture, which is on the charcoal canister line which comes out of the top of the "expansion tank" on the top of the tank.

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I'll take a photo of mine when home mate

Mine doesn't have it either, it's identical to yours, never been an issue.

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Originally Posted by Throbbinhood

Mine doesn't have it either, it's identical to yours, never been an issue.

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Ok cool, thanx mate. That makes me feel better.
I was contemplating whether I need to drill a hole on the metal pipe at the fill point and fit a venting valve+filter there.
Sounds like I don't need to worry about it.
Cheers.

P.S. I think, as Kallen advised above, charcoal canister line does the job of venting the tank to atmosphere, though I may have to find out whether the charcoal canister is blocked or not. I've overfilled the tank couple of times(to check fuel economy).
I might have flooded the charcoal canister by doing that and caused some damage to it.

Fuel fill point photos.

To be honest, if I remember correctly my breather line (the right angle one) was blocked off. I plumbed everything else up as per the LRA diagrams and it all works perfectly, even on hot days. So far has not been an issue and touch wood it doesn't become one in future.

Fuel cap photos

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Originally Posted by Throbbinhood

To be honest, if I remember correctly my breather line (the right angle one) was blocked off. I plumbed everything else up as per the LRA diagrams and it all works perfectly, even on hot days. So far has not been an issue and touch wood it doesn't become one in future.

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If we're talking about the one that allows the "breathing" when filling up the tank to cut out the petrol at nozzle when petrol if filled up to the fill hole on the tank, then only downside of that is you just have to manually control the fuel filling to ensure you don't overfill the tank. Since yours is straight petrol, even if you overfill it once or twice, you end up using few litres after that and end up not creating extra pressure inside the tank on hot days. Besides, any expanding petrol might get through the charcoal canister line and flood out of the charcoal canister eventually(assuming the canister is not blocked). So, I reckon chances of it can turn dangerous is pretty slim.
Besides, you have two tanks, don't you? That pretty much eliminates most chances of pressure build up accidents(assuming tanks are connected to equalize the pressure between them?)

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Originally Posted by dom14

If we're talking about the one that allows the "breathing" when filling up the tank to cut out the petrol at nozzle when petrol if filled up to the fill hole on the tank, then only downside of that is you just have to manually control the fuel filling to ensure you don't overfill the tank. Since yours is straight petrol, even if you overfill it once or twice, you end up using few litres after that and end up not creating extra pressure inside the tank on hot days. Besides, any expanding petrol might get through the charcoal canister line and flood out of the charcoal canister eventually(assuming the canister is not blocked). So, I reckon chances of it can turn dangerous is pretty slim.
Besides, you have two tanks, don't you? That pretty much eliminates most chances of pressure build up accidents(assuming tanks are connected to equalize the pressure between them?)

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The line I'm talking about is the 'charcoal canister line' in your first pic in this thread.

But yeah everything goes to the dual tank filler thing, from memory they are all interconnected etc. Honestly cant remember 100%, but it's sat in the sun in 40+c weather with full tanks and no issues.

Petty tanks aren't supposed to have a 'breather' direct to atmosphere
That is the job of the Charcoal Canister.

You should have the fill line breather that goes from your tank to the top of the filler so you don't get blowback when filling.
Both the filler and fill breather should be sealed from atmosphere with the cap on.
The tank 'evaporates' to atmosphere via the Charcoal Canister and not a separate line

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Originally Posted by Throbbinhood

To be honest, if I remember correctly my breather line (the right angle one) was blocked off. I plumbed everything else up as per the LRA diagrams and it all works perfectly, even on hot days. So far has not been an issue and touch wood it doesn't become one in future.

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Or did you mean the "charcoal canister line"(as it's connected in mine) from the top of the expansion tank?
If that's the case, that means "slow breathing/venting" isn't happening in your tank, and fumes just stay inside the tank.
But, having two tanks still minimizes your chances of any pressure build up accidents. Besides, some pressurized fumes might escape from weak points like fuel cap.
I've been wondering whether the fuel cap is designed to allow that to happen, 'cos if you look at the pictures of the fuel cap above, it doesn't look like a simple fuel cap, but some mechanism appears to be there at the bottom of it.