Fuel Vent Hose in Trunk

[4uall]

does this help?

[76was124]

Three Hoses from Tank To 3-Way Connector


Tank Vent Exit from Trunk


Vent Hose Connects to Vent Hard Line & Travels Along Transmission

I know this is an old post, but looking at the pictures with the two-way valve (labeled 1 way-valve in the picture) I think it is installed backwards. If I am looking at the picture correctly, Wide diameter end should be pointed to the back of the car or connected closest to the gas tank.

Also I finally confirmed a much debated discussion about that valve. It is a two-way, not a one way or commonly referred to check valve. It makes sense it needs to relieve pressure/vacuum depending on whether you are filling the tank or draining/pumping fuel out. I hooked up a hand vacuum pump both ways, and in each case the valve opened relieving the pressure differential. Whether one side trips at different pressure differentials then in the other direction I couldn't say for sure as it was too low of a trip point to see on my guage. However it did make a different sound opening one way then the other, and since the body size is different on one side vs. The other, I would guess it may have two different trip points.

[RRoller123]

Thanks, that adds to the knowledge base on this!

[TFichter]

I am so glad you wrote in about the photo of the 2-way valve. It has worried me for awhile. I thought it was in backwards as well and installed mine the opposite way of the photo because there is a small arrow on the valve indicating direction of flow. I also checked this by sucking on it to check the direction. After replacing ALL of the hoses going to and from my gas tank, as well as the sending unit and its gasket, I still have gas fume smells. The only items left are the tank itself and the vapor canister. Any thoughts on this? I have a previously owned 1982 Spider 2000 which I am trying to revive to its glory days.

[RRoller123]

My gas smell was difficult to find, but turned out to be an easy fix: the gas cap seal was bad and the fumes were getting out and settling into the trunk making me think it was a problem with the plumbing or the tank in there. New cap solved it instantly.

[TFichter]

Thank you for the tip! Sometimes it is the simplest solutions that are easily overlooked. I will try replacing my gas cap next.

[76was124]

I am so glad you wrote in about the photo of the 2-way valve. It has worried me for awhile. I thought it was in backwards as well and installed mine the opposite way of the photo because there is a small arrow on the valve indicating direction of flow. I also checked this by sucking on it to check the direction. After replacing ALL of the hoses going to and from my gas tank, as well as the sending unit and its gasket, I still have gas fume smells. The only items left are the tank itself and the vapor canister. Any thoughts on this? I have a previously owned 1982 Spider 2000 which I am trying to revive to its glory days.

You probably did the fuel fill hose too, but just in case you didn't that was a problem area for me as well as the overfill hose.

[TFichter]

Yes, did that too, but thank you. I think I will also look into adding a gasket sealant to the fuel sending unit seal. Perhaps something is just not quite sealed around that even though the rubber is new too.

[oschris]

The diagram in the factory manual looks like the wide diameter is towards the front of car (carbon canister side) Although yes all indication show label should be "two-way valve" - chris

[76was124]

The diagram in the factory manual looks like the wide diameter is towards the front of car (carbon canister side) Although yes all indication show label should be "two-way valve" - chris

Was that a metal, or plastic body valve?

[oschris]

Metal valve OE from Bayless. I had positive pressure in tank with old totally clogged valve. With new valve (identical appearance) I have strong negative suction in gas tank. installed orientation is with wide end towards engine (diagram in this post is other way?
Other alterations I put rubber cork in canister ( I see blue tubes picture has open canister) maybe will take that out.- chris

1984 spider pininfarina

[76was124]

Picture in original post has wide end toward engine(note trunk label). I believe that is backward.

However, your vacuum in the gas tank is because of the cork in the charcoal canister. The missing cap on the canister has a very small vent hole in it. To confirm, take the cork out and keep your thumb over the hole with the engine running. you will feel the vacuum form.

For a simple fix, drill as small a hole as you can in the cork...something around a 1/16 " or less. I had the same problem made my own cap and played with different hole sizes. Ultimately I spent the money and bought a new canister to help rule out an idle issue I had. Is your stopper an actual cork, or a rubber plug? I would avoid cork which could crumble and get particles sucked in.

[oschris]

Took the rubber cork out and all is fine, drove it that way for 30K miles prior. Car has always idled seemingly well though all these vapor line configurations -chris

[cajunfiat]

another tip once you clean the check valve. blow test the line from the tank to the check valve and then from the other end of the check valve to the front of the car that leads to the charcoal canister to make sure its not restricted. i had a bunch of syrup in my lines. once cleared you should be good.

[RRoller123]

The diagram in the factory manual looks like the wide diameter is towards the front of car (carbon canister side) Although yes all indication show label should be "two-way valve" - chris

Yes, it is a 2-way valve, designed such that fuel vapor air can pass in both directions. The inner spring baffle is meant to create a permanent internal pressure, on either side, or both sides simultaneously, and only when a particular differential is reached will it pass, and allow flow either way once that diff limit is reached.

On a very clean, or new one, you can blow into either end and sense what that release pressure is, it is not too high. It did seem to me that there was a slight difference in the pressure release depending upon direction, but I think this is likely an illusion (?), as the valve would be much more complex and it would serve little purpose?? Mine was gunked up badly with grey sludge and so I bought a new one and installed mine with my PERCEIVED (probably wrong) pressures this way: (just to make the whole conversation more confusing). I would be curious if anyone else senses this difference in release pressure depending upon direction.