Where does the vent valve trigger unit go? (pic)

[Dale_K]

I moved a gizmo that looks like a dynamite detonator on the gas filler pipe and now my car won't accept any gas when I try to fill up. I think this thing is some kind of trigger unit for the gas tank vent valve. Here's a picture.



Can anybody tell me how this thing works and where it's supposed to go? I think it was strapped down where you can see a line of tape on the filler neck. When I tie it down there and stick my finger down the pipe to fold the little door back I don't hear any kind of click or anything that sounds like a valve opening.

[Dale_K]

I'm making some progress and I'm no longer astonished when I discover the source of my problems is my own ignorance. About a week ago I installed what Porsche calls a "vent valve". My car was making a strange "wooo" sound and I didn't really know what was causing it but anything called a vent valve sounded like it could be the problem so I bought one online.

When the valve arrived there was a problem with the order. They failed to send me some o-rings I requested but I received something else I didn't order. It looked like a brake pad sensor to me.

Just a few minutes ago I realized the item I thought was a brake pad sensor is the same gizmo I called a detonator in my earlier post. Apparently when you order a vent valve it includes the trigger sensor for the gas tank vent valve. I saved the old part so I got it out of the bag and held it along the new trigger sensor that I thought was a brake pad sensor. You will not be surprised that they fit like they were meant to go together, lol.



The vent valve alone.



So I might know where the part goes. Now I get to do the job over. I imagine it might work as good as it did before I started when I'm finished.

[Dale_K]

Restoring the little detonator piece to it's rightful spot in the vent valve housing fixed it. I haven't actually put any gas in the car but I can hear one of the charcoal canister valves open (or close, I don't know which) and the sound of the tank exhaling when I push the little flapper open with my finger. I think there must be a magnet on the little flapper and the piece I call the detonator is actually a magnetic switch but that's just a guess.

Being a mechanic is hard when you have limited aptitude and skill, lol. My knowledge base is increasing in the areas of oil fill tubes, coolant bleeder valves and now gas tank vents. Not exactly what I expected to learn but still interesting in an abstract way.

[Wayne 962]

Thanks for the update! With all of the issues that people are having with these valves and this setup, we've decided to perform some tech articles on the replacement and document them on the site and in the 996 book!

-Wayne

[squireiii]

Have Wayne's tech articles come out yet? I'll be diving into this system soon, so I hope so.

[Dale_K]

A long time after I posted this thread somebody sent me a pdf file from Porsche that explains the technical details of most of the pollution control equipment on our cars, including the gas tank venting system. Here is one of the diagrams. PM me with your email address if you need the document.

[Kroggers]

Hi Dale_K, I will send you a PM, but could I please have a copy of that PDF document?

[ferrytrip1]

Hi, I too have the fuelling issue where it cuts out and takes an age to fill.

I looked at the valve 996.201.143.01 and founf it was loose with one of the tabs broken.

I will get a replacement tomorrow - question is- I see in this thread the Blue circular item that I belive is being referred to as the magnetic switch - I do not see this on my car - mine is a 02 base 2.7. Should it be there?

Thanks

Simon

[Mark at Pelican Parts]

This is an annoying issue at the very least! But we have the solution and also provide step-by-step instructions on how to replace your Boxster's fuel filler vent valve.

You can get this project done in less than two hours with minimal tools - problem solved!

Click here to purchase the Genuine Porsche replacement valve.

Take a moment and review our tech article on the topic:
Replacing Your Fuel Filler Vent/Bleeder Valve

Check out our YouTube video on the subject as well:
http://www.youtube.com/watch?feature=player_detailpage&v=8mg_hXSMj2U&list=UUEWqxhoc16V59Ni-SmElC9Q