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Old 05-25-2020, 08:23 PM   #1
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Join Date: Aug 2019
Location: Austin, TX
Posts: 15
Question about Fuel Vent/Bleeder Valve: reed valve and magnetic door?

Here are the basics:

2000 986 Base, 93K miles.

Got at Christmas (gift from brother -- have seven other of Ferry's cars, but none terribly "modern" 'til this Boxster -- yep in my collection, 20 years old is practically new).

Replaced IMS/Clutch/RMS, spark plug tubes, serpentine, exhaust (came with a new performance exhaust in the trunk). (Though a November 2000 build, it nonetheless had a dual row IMS, so probably didn't need to be replaced, but the piece-of-mind is well worth it.)

Car has made the fuel filler howl intermittently since I got it. Frankly, I thought it was a throwout bearing or water pump or something mechanical like that, 'til I finally got out of the car one time last week when it was making the sound, isolated it to the fuel filler area (which does not lock -- should it? if so, in what state(s) of operation?).

Car has no codes, no problem filling, runs great (I have a light foot, so only complaint is that I wish gas mileage were better -- both my '73.5 911 and '88 924 can get 30-35mpg on the highway: of course, they also top out at only 130-135mph, not 155).

I read about the "bottle top howl", and dove right in and replaced the vent/bleeder valve (I am more of a "throw parts at it" rather than diagnose it first kind of guy). Kind of a mystery to me how it works as there are no electrical connectors on it, and the valve itself seems exposed to the filler pipe without a gasket/seal, etc.

When replacing it, there was a 1.5-2" long thin rod-like wired sensor(?) taped to the filler tube below the vent valve, but otherwise dangling, which I left dangling -- is this the reed valve I've read about? If so where does it go? Does it clip in the valve somewhere? (btw, "reed" turns up zero hits when search the parts catalogue or service manual.)

Also, there was an orphan female connector with a white component thingy (like the size of a really big fuse or really small relay) in it also dangling in the vicinity of the vent valve. Any idea what this is?

Any advice on whether these two things are somehow associated with the vent valve would be appreciated.

Finally, with regard to the wheel liner, there is a bit of the liner that extends directly behind the strut coil and is secured with a push clip (a real PITA to get to). Does this bit of the wheel well liner go over or under the wheel speed/abs sensor cable and (battery?) drain tube coming out of the wheel well wall?

Last edited by austinporsche; 05-26-2020 at 05:12 AM.
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Old 05-26-2020, 04:55 AM   #2
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Join Date: Aug 2019
Location: Austin, TX
Posts: 15

Thread from 2011 explains a lot about general concept of operation.


I haven't pulled liner yet, but after looking up a picture of the Porsche Fuel Tank Bleeder Valve Contact Sensor (99661322401), the connector with the "white thing" terminated in it may actually be the connector for the contact sensor itself. (yeah, I've worked on a lot of cars in my life -- stupid is as stupid does).

The wheel liner has definitely been off before so maybe the previous owner had just disconnected it? The vent/bleeder valve, if not original, looked to be in there for some time as the red-orange cap on one of the two hose connectors was quite faded (Texas heat will do that to plastic -- even if no direct UV).

If the contact sensor is disconnected, the valves on the system (at tank and behind headlight) shouldn't open, and I should have the refueling issue, (fuel goes in, displaced air has nowhere to go, pressure builds, fueling stops), which I don't?

Car up, wheel off, liner out again. Ugh.

Last edited by austinporsche; 05-26-2020 at 05:14 AM.
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