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Discussion Starter #1
Does anyone know how much pressure the one way valve on the fuel breather line should need to open? Mine takes a fair amount of pressure to open and then it sounds just like a razoo when air goes through it.

My fuel tank always has a lot of pressure in it when I open it and I'm wondering if my one way valve is the problem.

It also explains the really strange noises which I hear coming out of the parcel shelf every now and then, especially on hot days.

Thanks.
 

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Assuming it is the same/similar to the L-jet Spider's valve - very little. A gentle puff of lung power. But I don't know how many PSI's that is...

On our Spider I have cleaned it and restored it to good working order with a spritz of carb cleaner.

A quick search in the Spider section revealed this: gas tank sounds like it is boiling
The procedure is on 4-15 of the manual. Looks like the opening spec for valve 3 is 0.36 PSI, which means that's the most pressure the tank should see.
 

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Discussion Starter #3 (Edited)
Thanks. After cleaning it, it still makes weird noises even though I'm guessing it doesn't take more than half a psi to blow through it - a firm breath.

:eek:. Do all gtv6s make this noise?
 

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Assuming we are talking about a SPICA car, that little valve is not for pressure relief; it is for preventing the engine from pulling too much vacuum on the gas tank. If you tank is building pressure, is is probably because the outlet of the charcoal canister (the outlet has a tiny restrictor [about .015" dia] to limit vacuum flow from the engine) is clogged. I had this problem crop up on my car for the first time about 6 months ago. (I was getting large positive pressure in the gas tank at all times.) I opened up the hole in the canister outlet; no more pressure build up in the gas tank.
 
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