mistergrumpy
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| posted on 26/10/07 at 09:44 AM |
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Fuel Tank Vent
Can I just clear up a bit of confusion on my part. On the vent on my tank do I need to put a 1 way valve to let air in and keep fuel in or I'm
sure I've read somewhere that you can just make like a U bend from fuel pipe and bang a little filter on top. Just to confuse things firther,
I've seen cars with just a filter directly on the vent.
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Duncan_P
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| posted on 26/10/07 at 09:58 AM |
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To be on the safe side I bought a proper breater from here
If you have injection then I believe you should really have a 2 way valve instead of a 1 way one to allow any build up of pressure in the tank to be
released.
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Jubal
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| posted on 26/10/07 at 10:29 AM |
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I had a lot of confusion over this too. When I got it my car was fitted with a breather pipe only and on every right hander petrol found it's
way out. I got black flagged first time out because of it. I just fitted a one way check valve in line into the breather pipe which lets air in and
out under normal circumstances but will activate when the flow of petrol hits it. Never had any probs since. But it's never been tested in a
roll over... 
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RazMan
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| posted on 26/10/07 at 10:30 AM |
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Many people use simple breather valves but forget that you need to let pressure out AND let air in to replace the fuel used. There are any number of
sophisticated 2 way valves available but at £30-40 each they are rather expensive.
Many racers do it with a simple breather pipe going up as high as you can and then dive under the tank with the exit below the tank bottom. Doing it
this way ensures that if you end up rolling the car, fuel cannot drain out whatever position you end up in.
I also use a fuel filter in the tube which acts as a buffer for the little surges caused by sloshing - they fill the filter and then drain back into
the tank.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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mistergrumpy
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| posted on 26/10/07 at 10:37 AM |
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So thats a two way valve you're talking about is it? As oppose to the one way. Waht pressure do I need to let out of the tank? I'm on
carbs if that matters.
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robertst
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| posted on 26/10/07 at 10:56 AM |
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what about getting a length of rubber fuel pipe and coiling it to the side of the tank? IIRC thats what has been reccomended here a while ago...
Tom
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Paradoxia0
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| posted on 26/10/07 at 11:58 AM |
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When I took my car for SVA I was told that you could aparently use a length of pipe mounted as high above the tank/filler as possible with a
"pigtail" coil in it. This will allow the tank to breath and not allow any spillage under normal use, but if you rolled it I think a
puddle would quickly appear...
I went for a proper fuel breather on mine.
Don't know if that helps any, possibly not!
Mark
There is no replacement for displacement...
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vindicator
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| posted on 26/10/07 at 02:43 PM |
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I am still looking for one....problem for me is that I only have 3-4 inches of height above the tank before the breather pipe touches the top of the
body work and that is also where the filler cap is....
Also looking at the valves at thinkauto and merlinmortorsport (all the same) you have to either get your hand inside the tank to fit the nut onto the
valve or screw it in.
I don't know what thread my breather pipe is attached too, to the tank, so I am still ermmming and arrring.
Once I leave work tonight, I'll get a photo of what I have done so far....still does not work!!!
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mistergrumpy
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| posted on 29/10/07 at 08:47 PM |
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Just to finish this then. Do I need a 1 or a 2 way valve for my carbed ZX9?
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