Fuel Breather
Daddylonglegs - 29/8/11 at 10:17 PM
Having an issue with vacuum in the fuel tank (at least I know the mechanical pump has a good suck! ).
I know I need some sort of breather to allow air in as fuel is used, and have been researching in various places and decided that I am going to try to
use a pipe from the vent pipe on the top of the tank (it's off a Triumph Spitfire) and run it higher than the tank then loop back to below the
tank. This should stop fuel escaping under normal conditions and prevent leakage in the event of an overturn 
Anyone have any feedback on this and is it gonna get through the IVA like that?
I've searched for one-way valves but they seem stupidly exoensive anodised things! I just wanted an in-line type.
Thanks.
JB
Myke 2463 - 29/8/11 at 10:28 PM
290402089270 ebay £3.95 post free.
blakep82 - 29/8/11 at 10:36 PM
i've got one like that, but i'm not sure its right
it needs to let air in to replace used fuel, but let pressure out in case of vapours from expansion (hot day) but not let fuel out if rolled over
surely? so needs to let gas both ways, and liquids one way?
the cheap way would be to have your breather pipe go the whole way around the tank, so that whatever way up the car is, the breather pipe is ALWAYS
above the tank... not sure how a IVA tester sees it, or do they even check?
[Edited on 30/8/11 by blakep82]
dlatch - 29/8/11 at 11:47 PM
quote:
Originally posted by Myke 2463
290402089270 ebay £3.95 post free.
it looks like the right one but not 100% sure
the proper ones are not strictly one way valves as they will let gasses out but they have a ball that will seal when liquid gets to it (in the event
of a roll over)
daviep - 30/8/11 at 07:36 AM
I did mine with a loop of hose and passed SVA no problem, I prefer this solution to a valve as it is 100% reliable.
Here's how I ran my hose, notice it's run from the top of the tank at the front and then looped down and along the bottom of the tank at the
rear, this prevents fuel leaking no matter how the car lying.
breather hose
Davie
[Edited on 30/8/11 by daviep]
wicket - 30/8/11 at 08:04 AM
^ same here
[Edited on 30/8/11 by wicket]
Daddylonglegs - 30/8/11 at 08:15 AM
Cheers guys 
I think DavieP's idea seems a good bet. If it passed the SVA I cannot see why it shouldn't pass the IVA? I'll just have to take the
risk and find out the hard way 
Thanks.
JB
karlak - 30/8/11 at 08:54 AM
quote:
Originally posted by daviep
I did mine with a loop of hose and passed SVA no problem, I prefer this solution to a valve as it is 100% reliable.
Here's how I ran my hose, notice it's run from the top of the tank at the front and then looped down and along the bottom of the tank at the
rear, this prevents fuel leaking no matter how the car lying.
breather hose
Davie
[Edited on 30/8/11 by daviep]
Did mine the same but had to put a couple of "loops" in the fuel pipe as it exit'd the tank and then headed 'downwards". On
a fullish tank of fuel and hard cornering, I did sometimes have fuel find it's way out of the vent and down onto the road - Really annoyed anyone
following me in another "7" car - did'nt it bass1st 
I guess it depends how high you can take the vent pipe before you need to turn it downwards.
myke pocock - 30/8/11 at 09:26 AM
This one was asked recently but I cannot find the answers so here is my reply again. I used a coil of brake pipe, drilled into the inlet and fitted a
nutsert. I then glued the coil in place with Araldite and it passed SVA. NOt sure about IVA though but why not?
daviep - 30/8/11 at 03:21 PM
quote:
Originally posted by myke pocock
This one was asked recently but I cannot find the answers so here is my reply again. I used a coil of brake pipe, drilled into the inlet and fitted a
nutsert. I then glued the coil in place with Araldite and it passed SVA. NOt sure about IVA though but why not?
I personally don't like the above solution, if the car ends up on it's side or upside down then fuel will be able to run out of the
breather, not a nice thought if god forbid you happen to be trapped in the car.
If you look at the way my hose is run then you will see it doesn't matter which way you turn the tank fuel cannot escape.
Davie
Johneturbo - 30/8/11 at 03:39 PM
i did something similar like daviep on my first car, i run mine down and back up past the top of the tank works the same way
i bought the righ breather from thinkauto but not cheap think was about £25 lets air in and out but stop fuel escaping in a roll over
