Problem fueling after replacing AOS

[hogswan]

2001 C4, Manual, Coupe

Preemptively replaced AOS last weekend in preparation of track season. Since then, I have not been able to fill-up with gas. Can get in about 0.3 gal before pump handle automatically shuts off and I start seeing gas at top of filler tube neck. Gas gauge reads empty which is in accordance with mileage since last fill-up.

I have not CELs, no noticeable vacuum noises, and no running issues. I have checked the fuses (E6) and swapped the fuel filler vent /bleeder valve with another used one that I have no reason to believe was not previously working (no new ones in the US right now).

Next step is to check all the related vent lines for obstructions. However, this seem too much of a coincidence with my work on the AOS. Any thoughts as to something in the engine bay that I may have goofed up that would be causing the fueling/tank venting problem?

Thanks in advance for your help.

[EleCTriCT]

if your battery is disconnected on a twin turbo or a c4s with out a certain amount of fuel in the tank you need it re calibrated....

it is a quick thing but you need a scanner such as piwis to be able to do this.

once the fuel goes below a certain amount because of the saddle tank design the fuel gauge works on fictional readings. the tank be full but the gauge will only display about a 1/4 tank full..

Also by the top of the filler neck there is a little cylindrical magnet type sensor with a wire. it is up in behind the wheel liner, if this is disconnected or incorrectly installed this will cause filling issues

[judgejon]

right. the connection to the vent valves should be checked. try pushing open the flap that you can see looking down into the gas filler pipe. Listen carefully. you should hear a slight click sound if the solenoid is connected properly. There's another vent that can cause the problem and the switch is located on top of the gas tank, under the battery tray. If either of these are not connected there's no air vented from your gas tank and you can't pump in any gas. You can fill the tank, just be ready to dribble in the gas about a filler-tube amount at a time, or one half squeeze on the gas pump handle. Takes about 30 min. Been there, done that. good luck.

[judgejon]

ps: also check the fuse for the gas filler valve. I forget the number. check the fuse list, its on there. this topic, and the fuse #, is also covered more extensively in the forum, check on the search engine.

[hogswan]

Thanks for suggestions but had already tried all those options to no avail.

Finally tracked issued down to mice having eaten through the wiring for ORVR valve on top of fuel tank. This must have happened while I was replacing the AOS at the opposite end of car. Car was fueling fine prior to this project. I guess we can say the AOS replacement was temporally but not technically related to the EVAP/fueling issue.

On C4s, and I suspect C4Ss and Turbos, this wiring and valve is only accessible by dropping fuel tank from car which requires dropping front drive/differential and much of front suspension. Nutty amount of work (done by shop) for a mouse/rodent?

Bright side is that I'm now very familiar with EVAP system for AWD 996s!?

Thanks.

[judgejon]

Same thing had happened to me. Exactly.

But my fix was done via removal of battery and battery tray. Nest, and valve wires underneath.

Check my topic and posts on this issue for the whole story.

Glad your problem solved. Always big bucks, right? And for a darn mouse nest....oh well

[judgejon]

Check my post under "gas filling problem solved" for the full story.