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Working from memory here, so bear with me: To gain access to the canister remove the black plastic cover over the brake booster. Its in front of the battery, near the center of the vehicle but slightly towards the pass. side. The cover is held in with maybe 8 Philips screws. Once that is removed you will see there is a plastic bracket that holds the canister to the body, if I remember right its held in with a T40 screw. After that you have two "quick" disconnect lines on the bottom of the canister and one electrical connector on the top of the canister. Its kind of a beast to get out, the connections on the bottom of the canister are tricky to get to.

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On 3/15/2021 at 4:37 PM, JFP in PA said:

Working from memory here, so bear with me: To gain access to the canister remove the black plastic cover over the brake booster. Its in front of the battery, near the center of the vehicle but slightly towards the pass. side. The cover is held in with maybe 8 Philips screws. Once that is removed you will see there is a plastic bracket that holds the canister to the body, if I remember right its held in with a T40 screw. After that you have two "quick" disconnect lines on the bottom of the canister and one electrical connector on the top of the canister. Its kind of a beast to get out, the connections on the bottom of the canister are tricky to get to.

 

Your memory is exactly right --  it's easy to get to but hard to get the connections off.

Anything in particular I should be looking for in this area?

 

Ive read about others having issues with the purge solenoid in/near the intake but I don't have any codes, so I wonder if my problem is upstream...

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One of the valves associated with the canister acts as a vent for the gas tank and can cause problems when filling the tank.  I would examine and test the valves to make sure they are functional. 

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11 hours ago, JFP in PA said:

One of the valves associated with the canister acts as a vent for the gas tank and can cause problems when filling the tank.  I would examine and test the valves to make sure they are functional. 

Got it, thanks.

 

So, as far as I can tell, everything looks normal.  I wasn't able to get inside the portion of the evap canister pointed at in red, but it seems to me that part is not meant for disassembly:

image.png.e3972b05e0da45dd0397a48fea4f3b14.png

 

What should I expect to see on the filter housed in part [8] if everything is functioning correctly? Because mine is just a little dusty but otherwise looks clean, no smell of fuel.

 

***

 

 

 

I want to document a few things in case it's helpful for others, because I had a tough time wrapping my head around the system's routing without taking everything apart (it's not obvious from the parts catalogue to a dumbo like me) and there's very little information out there about the 987[/997?] in this regard.

 

There are of course two tubes that connect to the canister at its bottom side. The tube designated [2] in the above schematic runs from the bottom of the canister (the driver side connection) to the top of the gas tank -- right underneath the battery. We'll call this "Tank Tube" for this post.

 

If I'm not mistaken, the other (smaller) hose connected to the bottom of the canister (and specifically the connection on the passenger side) is the super long part [4] in the picture that follows:

 

image.png.8e31f83863e0ea92e81579fa8c0622d9.png

 

If i'm not mistaken, that particular long tube [4] runs all the way to the purge valve in the intake. We'll call it "Purge Tube" here.

 

To remove the canister, I disconnected the Purge Tube first. It's not easy, as it has two tabs -- one hidden and obstructed, facing ~2 o'clock and the other visible at ~8 o'clock (if the rear of the car is at 12:00). I don't think there's enough room for fuel line pliers. I figured out a way to get it off by carefully levering a right angle pick against the thicker Tank Tube into the tab facing 2:00.

 

The Tank Tube by contrast has a large tab encompassing roughly 8:00 to 2:00 that requires some contortion if you have big hands but is relatively easy to get off once the Purge Tube is disconnected.

 

My Tank Tube (again referring to [2] in the first schematic) is clear with no obstructions, and I smelled gas when I disconnected it from the tank, so it doesn't appear there's any obstruction inside the tank or fuel pump assembly itself.

 

By process of elimination, here are what I perceive to be the potential remaining culprits:

--something clogging the inside the sealed part of the evap canister (red arrow above), for example from someone topping off the tank previously

--something inside the fuel filler neck (going to try to put a siphon in it and see if I run into any obstruction on the way down)

--Purge Tube [4] or the purge valve is obstructed/malfunctioning (but I believe I'd be getting a code if that was the case? In any case I'm going to get into the manifold and make sure there isn't any obstruction in the tube)

--(other possibilities?)

--nothing's wrong, my car is just picky, and I need to fill it up slower???

 

Edited by Far M
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One of the biggest problems is that Porsche stopped publishing vehicle service manuals after 2004, going to an online system that is built into the PIWIS system, which is a lease only diagnostic system with a first year's lease at $20,000.  So basic service information became very scarce.

 

To my knowledge, the filter unit itself is not very prone to causing problems.  I would make sure all the lines were free flowing, blowing them out with compressed air to be sure, and that the valves were tested for functionality (they are a simple open/closed action, operated electrically).

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  • 4 weeks later...
On 10/24/2010 at 11:06 PM, leszaj said:

I figured it out. I had to remove or loosen the manifold by unscrewing 4 bolts then I was able to get to the purge valve. I had to cut the hose a little because I couldn't remove it with the tight space. Then I folioed the vent line attached to the purge valve all the way down into the wheel well almost. I had to remove the tire and then at tech the vent line. It was pretty tedious but I did get it. Because space is very limited in the engine space. Thanks everyone for your help.

 

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