Hi guys,

a lot of talk on many threads about what breathers etc to use for the fuel tank breather.
Reading the IVA, it only really mentions:

"The fuel tank must be fitted with a vent (to permit release of a pressure build up) which does not exit on to the exhaust or into the vehicle or be situated at such a height that fuel would be likely to leak when the vehicle is driven."

So from this, I would think that a simple one way, roll over valve like this

https://www.carbuilder.com/uk/fuel-roll-over-valve-6mm

And a filter like this, positioned high up in the rear section

https://www.ebay.co.uk/itm/Pit-Dirt-Quad-Bike-fuel-cap-breather-pipe-gold/254162497296?hash=item3b2d43ef10:g:~EwAAOSw5cNYQy46

What are your thoughts?

I have used one of these inserted into a length of pipe with an air breather filter on the end, no issues so far.

https://www.demon-tweeks.com/uk/atl-tank-vent-valve-6-vent-inline-to-suit-6-hose-3-8-hose-barb-atltf-af-004/

Hi,

My pipe is all 8mm

also, does that contain a one way valve, hard to tell?

On my MK Indy I didn't fit a one way breather, simply a length of fuel hose that ran down the side of the fuel tank to below the base of the tank. It prevented any pressure build up inside the fuel tank and had the car gone upside down it would have done the same without allowing fuel to drain out of the tank (assuming the tank hadn't been punctured).

Passed SVA without an issue - I've not IVA'd a vehicle so I'm not familiar with what the current rules may or may not be.

the tank needs to vent both ways as when fuel is burnt, the tank would implode / engine suffer from fuel starvation, easiest way is a length of brake pipe with a coil wound into it a bit above the tank and exiting into the air near the chasis bottom rail.

drill a small hole in the fuel filler cap..... only needs to be 0.5mm if that!

As Nick205 has done, i've just run some rubber tube up and back down, passed IVA like this and never had a problem

quote:

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Originally posted by pekwah1
As Nick205 has done, i've just run some rubber tube up and back down, passed IVA like this and never had a problem

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Guess I could run a pipe up and back down and fit the filter end on too

quote:

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Originally posted by ttalps2000
drill a small hole in the fuel filler cap..... only needs to be 0.5mm if that!

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I have fitted a simple length of tube with a bend then down below bottom of tank, big error. The top of the bend is not above the top of the filler cap which means if I overfill I could have about 300 ml of fuel draining out on to the forecourt floor. Will be fitting a valve.

[Edited on 28/12/20 by shortcircuit]