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Discussion Starter #1
So my car is wonderful except for this teeny tiny issue regarding the process of filling it with fuel. It likes to click the pump off every dollar or so.

I've done a bit of looking around, and here is what I've done so far. It seems quite bleak.

I've disconnected most of the vent lines and blown air into them to try and free up valves, but it has not made a difference.

A borescope camera showed a clear fuel path from filler nozzle to tank.

Charcoal canister is clear and open.

I believe the problem is with the "fuel tank vent valve" that has two functions: A spring operated valve lets vapors out to the canister when there is a pressure differential. So when it's being filled, the vapor pushes out towards the canister. And when the engine draws a vacuum on this line, same thing. Another function it has is to have a small float on the bottom, when the fuel level is full, it pushes on the float and closes the valve so it shuts the pump off.

Can I just say, this evap system is the most complicated system I've ever seen. Why??

Here is where I think the problem is, I've highlighted the relevant hose in red and the problem valve in green. This is the description according to the service manual.

G: VENT VALVE
The vent valve is incorporated in the fuel tank. During filling the fuel tank, fuel vapors are introduced
into the canister through the vent valve.
When the fuel vapor pressure becomes higher than the atmospheric pressure and overcomes the
spring force which is applied to the back side of the diaphragm, the port toward the canister is
opened. The vent valve also has a float which rises and block the port toward the canister when the
fuel is full.


What I've done is blown air into the filler neck, and it can't come out. It makes a strange noise and takes about 10-15 seconds to slowly drain out of the tiny tiny vent line that comes up to the top of the neck. In reality, it should, if I understand this, go to the canister and vent out of the fresh air port after being filtered. To verify that this isn't just a clogged canister, I disconnected the red line where it branches off to go to the intake solenoid. I blew air into that, and a friend listened, and heard air effortlessly venting out of the canister after passing through it, with no restriction. But when I blow air into the tank, it does not go to the canister, no noise of venting at all.

So I think item 16 is stuck closed. Anyone have any better ideas?

The reason this is bleak is it means I'll have to take the tank off. But I was looking at the car on the lift, it looks like you have to take the entire differential, driveshaft, suspension arms, exhaust, etc, off to get the tank off. Is this true?

Thank you, I hope I can get this sorted out!
 

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Fuel tank doesn't vent

Did you ever get a solution to this problem? I would concur that there is a vent valve problem (I have same on 2005 OB) but there is no vent valve in parts list for a 2005 OB. Unless it is integral to fuel pump assembly or the fuel pickup. However, the tank to canister line and the fill neck vent line both go straight into the tank and not a valve. I too can pressurize the tank.
 

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Discussion Starter #3
Still no real solution. At this point I may come up with my own auxiliary venting using a solenoid and antirollover valve.

As for there being no vent valve on the parts list, my theory after taking to a few parts department people is that it is a valve built into the tank and can not be removed.
 
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