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But Mad North-Northwest
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Photo is correct for an S4. Hose from the bottom of the part labeled "check valve" goes forward to the engine. Hose from the bottom of the vapor tank goes to the gas tank.

It looks like yours is a bit misconfigured: the air inlet should be on the other side of the check valve. Make it look like the photo.
 

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And check the air inlet & check valve (aka one-way valve). They can get gummed up and stick closed. Squirt some carb cleaner in them, shake, rinse & repeat until you can blow through them in the correct direction but not backwards.
 

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But Mad North-Northwest
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Actually the plastic one he has (unlike the earlier metal one) flows both ways. From black side to white side it flows very easily, from white to black it requires a few PSI to open. Don't ask me why, this shouldn't be necessary with the air inlet valve present.
 

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yes the black/white plastic one flows easy one way, and requires a few psi the other way.
an easy to find replacement for that valve is the VW part 058 905 291K
S4 set up here (worth checking the thin plastic pipe that fits into the tank is free. Generally they are, unlike the earlier spiders with metal tubes):
vapour valves.jpg

(dis-regard the shadow of the small pipe in the photo, that makes it look like 2 pipes....)
vapour1.1jpg.jpg
 

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Discussion Starter #7
My setup only has the check valve with no air inlet valve present. I wonder why the P/O would of illuminated that valve? Your setup appears to have a T connector for both valves. Can that be why I have such a heavy gas smell in the ****pit?
 

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But Mad North-Northwest
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Raw gas smell can be a leak anywhere in the system. Common culprits are the seal at the top of the tank (look for any moisture) or a cracked vapor separator tank.

It can also be caused by fuel tank overpressurization, but the way your vent system is set up I think it'll work okay. The check valve and hose are there, so vapor can properly flow forwards to the carbon canister. The yellow valve you're missing is to let air into the tank to relieve vacuum. But the newer white/black check valve you have also allows flow backwards from the carbon canister (which is vented on the S4) so theoretically you shouldn't have tank pressure or vacuum issues.

That said, were it me I'd probably put it back to stock, but it's not obvious to me that that'll fix a fuel smell problem.
 

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I'd get it back to how it was designed.
Check also that the evaporative solenoid (little electric gizmo attached to OVS mounting bracket) is operational ...when you apply power to it, should you be able to suck through it.
That allows gas vapours through the charcoal canister into the engine to be burned up, when the computor tells it to.
 

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Discussion Starter #10
Gas tank was removed cleaned and coated with some type of gas resistant epoxy. haven't checked the vapor separator tank for leaks or cracks. Ran twelve volts to that solenoid and I heard clicking when applied. it doesn't appear I have tank pressure reason why I'm saying that I have a little less then 1/4 tank of fuel left it's almost 90 degrees here after about 1 hour of driving I opened the gas cap and I didn't get that swish sound. Any idea where to find that air inlet valve or something interchangeable?
 

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But Mad North-Northwest
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Probably something like this will work? This one is for a 1/8" hose but they have other sizes (you'll need to measure the hose.)


Or just Google 1/8" check valve or 1/4" check valve or whatever it is. You just need something that'll let air in but keep gas vapor from escaping.
 

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the inlet valve (the yellow one) is PN 60507127
some suppliers in UK have them but crazy prices.

on ebay UK there is a whole tank with the 2 valves and the correct T piping that you might need, affordable too.

Maybe just make him an offer on the hoses and valves (the seller is an alfa breakers yard, known to UK alfa community)....postage to US would be cheaper that way, and he can still sell on the tank;)
Alfa Romeo Spider Series 4 Fuel vapour tank | eBay
 

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Discussion Starter #13
Thanks Gubi and Dom for all your input,recommendations and photos it makes this restoration that more fun.
Stay Safe,
Chuck
 
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