i'd file that under "learning the car". fueling it actually requires a bit of technique. that and learning the innate inaccuracy of the fuel gauge..

and as can a good woman.. this car will keep you guessing

 

Hi all,
I'm now retired and have more time (kids all growing up and independent with jobs) and start working/refreshing my 2001 996 TT. The car has 21,000+ now and still have the fuel filling problem.
I have just completed the following:
- Reconnecting the knock sensor wiring on banks 1 and 3 and pinned six coolant pipes on the driver side (see my post

"Some Creatures (may be rodents) Chewed Off My Wires")

- Replace oil/filter
- Replace coolant tank expansion, check all vacuum lines and replace hoses/coolant.
- Replace brake fluid.
- Replace Transmission and gear oil.
- Now I'm continue chasing my fuel filling problem. I've just replaced the charcoal canister and the car still would not take in gas (see attachments).



The next step I plan to do is follow recommendation of member RennFab
"cannot get ANY fuel into the tank your flapper valve is likely stuck closed. Just did the quick fix for this on a car here. Go to your local welding supply shop and buy a standard length of 1/8" aluminum Tig rod. Bend a VERY slight arc to it, and put a 90 degree bend in it 32" from one end to help twist it around if necessary as you're feeding it down the curves of the filler neck. Valve is located 29" down from the sealing lip of the filler neck.".

Anyone know what is the function of the blue valve in the picture? Should I try to disconnect it and check to see if there is flow through it?
It has been more than ten years since I joined this community and get help maintaining the car and start chasing this problem, a lot have happened since then but I'm so glad that I'm back, still healthy and continue be able to work on my car and enjoying it.
I will keep you posted of my finding.
BV

 

I inserted a slightly bend 36 in length by1/4 in diameter aluminum rod. I only can push down approximately 32 in measure from the filler neck. The inserted end was bended 80 degree to try to wiggle through the section between the filler pipe and the neck of the tank.
It seems that I can't push any further beyond that point no matter how much I rotate the rod.....
My CCTV camera has just arrived so I inserted the camera through the filler neck. From the video it seems that there is no obstruction from the gas pipe all the way down to the tank.
Anyone have any other suggestion of what I need to check next?
Thanks
BV

 

I searched and found some 12 year old post of mine and if this does not solve your issue re replacing the fuel vent line which is the only causative malfunction I've ever had - or known of?

then can't help. GL with it.

 

Thank you 02996ttx50,
based on your original recommendation, I did replaced the fuel vent valve. Still not fixing the problem.

 

only thing remaining I can imagine it *might* be is a bad electrical connector to whatever is activating the "flap/vent" activation.

must be frustrating but again, replacing the valve is all I ever had to do. GL with it. no fuel is a real problem!

 

Thanks @'02996ttx50. The flap valve seems to be working because I can hear a click when I press the metal gate at the neck of the filler.
One good thing is I've been able to put in gas all of these years but at a very slow rate by barely pressing the pump nozzle handle. It take about 20 min to fill up the tank and by then your hand is all sore up because you're trying to gently hold the nozzle and press lightly at the same time.
Back then around 2013 I did brought it in and paid P dealer to diagnose the problem. Their diagnostic (with some guessing) were there could be some wirings that was chewed up by the mouses that causes some valve not opening and the location they said is above the front suspension. They said they need to drop the front suspension and then the gas tank to investigate where is the problem.
I was hoping that some expert member here can give some idea of how the fuel and valve system work so that I can slowly check and eliminate all components that I can reach first before I have to absolutely need to drop the suspension and fuel tank when time come.
...Now it has became my obsession trying to figure out this problem...
BV

 

I just noticed you've been dealing with this since 2013?! wow.

only last thing I can add is that given your ability to DIY I would trace ALL wiring. thats all it could still be! ( guessing of course ) good luck.

if you don't have a schematic? I would reach out *here* to @jpflip who might just have one handy as he posts schematics often.

the man can fix airplanes lol

 

Of course I can help. The wiring diagram manuals can now be found on Rennkit site and many others manuals....

• 996 / 997 Turbo Factory Manuals

 

Thank you @02996ttx50 and for the info @jpflip. I'll start looking at the wiring diagrams even though electrical is one of mine weakest point. I assume that I'll start looking at item number 7.

• 2002 Turbo Wiring Diagrams, HER

@ @jpflip Unless you can point me to a place to start. Again, my gas problem is it does take in gas at a very slow rate and I have replaced and check most of the components under the passenger (right) front wheel next to the gas fueler. My assumption is there is an electrical line somewhere that is shorted or truncated and therefore won't allowing the gas tank to vent properly. As a result, when pump gas, the gasoline backing up immediately when you squeeze the nozzle all the way but if you gently (slightly) pull the nozzle (approximately 8 to 12 pennies per second) it will slowly take in gas.
Help please.
Thanks
BV

 

Still incredible all the work done to find the cause of your problem! Unfortunately I have never worked or had any problems with the fuel system... I re-read this whole thread and I really don't have any suggestions.... Sorry....

 

I guess you already check for any fault code. I was looking at the OBDII manual and all the fault related to the fuel tanks, here's the list:

 

Thank you jpflip,
the last table of codes give me idea to work with. I'll borrow my friend Durametric to recheck again to see if there are any code.
Last time I had CEL ran the check and it threw all kind of codes because of MAF and mice chewed up my knock sensor connection on bank 1 and 3.
Those problem were fixed at the same time took the opportunities to pin 6 coolant pipes on the left, replace expansion tank, fuel filter and replaced all fluids and no more CEL. The car run great....except the twelve year olds fuel issue...
BV

 

I think I found my problem!!!
Using the new acquired CCTV camera and slowly checking everywhere around fuel filler, inside passenger wheel well' s cover, under battery tray and finally remove carpet at the front trunk and look through a little hole under the CDs changer where the fuel tank vent valve is located (also known as ORVR) look what I found.


The old mice chewed up the wire that is supposed to connect to the fuel tank vent valve (996-605-203-01). As a result, it caused the valve to shut off all the time and therefore I only can pump fuel very slowly (55 min to fill up the tank by pushing down the tap at the filler neck at the same time to release pressure).
Now the next phase of figuring out the way to fix this is going to be interesting because the little hole that I sticked the camera in is only one inch in diameter. I'll have to gain access to that location to unplug the electrical connection and rewire the truncated wire.
I've read somewhere before that a member enlarge that hole to ~ 4 to 5 inches by cutting the aluminum section around the hole (black drawing) to change the defect ORVR valve.
Other than enlarge the hole, the official way to gain access to that location is disengage the steering, drop the front suspension and drop the fuel tank (seems like a lot of works).


I would welcome any suggestion of how to approach this problem.
Thanks
BV

 

All I can say is WOW. Glad you likely found the problem, tough call on what to do, I'm sure if you were to enlarge the hole, you could find a nice black cover/cap for the new sized hole. I guess it depends on how you feel about your car in relation to modifications. The difference between the 2 jobs is vastly different. I would probably enlarge the hole if it were me. Good luck and congrats.