Keith, I believe the connection at the top is what tells the DME that it's over it's below limit value. By looking at it. See pic below.
The 986 PTE shows the purge valve at the manifold. And so does the Bentley manual. But from other things I have read. It's electronically controlled on the other cars I have seen info on. But there are no electric connections on it at the manifold. I can find. So the only thing I can think of. Is when the car sits. There is a vacuum created in the canister that pulls the purge valve closed at the manifold. Which makes since. Since like JFP pointed out. It's a closed system. If the purge valve sticks open. Then the DME sees crap it doesn't like and sends the engine into a tizzy. Which could be caused by the canister not working and releasing pressure in the wrong direction. It won't suck anymore in from the line that goes to the manifold.
Since it seems like the DME on these things makes all the wrong decisions. Or should I say. One's that I don't understand? One more reason to refer to it as she.
The one in the pic is one I found off of a totalled 986 with half the miles on it than mine for $49.00 bucks. At this point. I'm about outa bucks to spend on it. And naturally. After some research. MY 99 can have three different ones. Ranging anywhere from $147.00 to $247.00 Guess which one was on mine???
I'll blow the line clear, (purge line). Put this one on and see what happens after I'll clear the codes.
New fuel pump will be here tomorrow. And down the rocky road I go. Anyone up for a "Diary of a Charcoal Canister" thread
But hey. At least my tires are new.
Are we having fun yet??? Randy