Filling the gas tank, what can we eliminate

[lechCe]

Hi guys, I have a constant problem with the filling of the gas tank. Its 2000 2.7Boxster.
There were different threads on that issue, but hard to syncro the answers from them.

What goes wrong, and what I have tested:
-whenever I try to fill, it pops out as if the tank is full
-there is no smell of petrol in general
-there are no strange sucking noises

I have tested the small plastic tab next to the inlet, it doesnt change anything in my case. I also took out the bleeding valve that looks fine as operative. There is a magnetic sensor on it as I see? I guess this works fine.

I though of changing the vent valve which is just beside it, this will be my next step.

Looking at VIN specification I have the charcoal filter in my car, but I guess this would not cause the filling in problems?

[mipstien]

I had a problem with filling my tank at one point. It wouldn't take fuel faster than a trickle and if I tried it came right back out at me. It ended up being the fuel fill magnet. The magnet became dislodged and wasn't doing it's job.

The part that the magnet lives in is #12 in this picture.

[Bill Ladd]

I also had the same problem in my 2000S. Turned out to be the fuse.

[robdelorenzo]

I have this same problem. When I am filling my tank, empty SUV’s come and go from the pumps while I am still filling up. Does the whole valve (#12) need to be replaced? What are some advised steps to diagnose the culprit? The tab next to the filler activates when I stick a key or credit card into it. But, it does not affect the problem. Is the magnet mentioned attached to the back of this valve (out of sight?) I saw it mentioned in a thread that not exchanging the magnet from the old valve to a new one will render the new valve useless. It also stated that the magnet is not mentioned in the valve replacement descriptions in both The Bentley and the 101 Book. Can anyone with experience in this please elaborate a bit more? Is the magnet similar-looking to the “pill” in the key fob? What am I looking for before replacing the whole valve? I time my pit stops when refueling with a sundial at the moment. I’m also tired of my shoes smelling like gas. Time to address this. Thanks -

[Benitom]

I just hold the gas pump vertically and manually fill it. Mine always popped as if it is full. I could be wrong but I guess older 911's are filled that way.

[mipstien]

I am not sure if the entire thing needs to be replaced. I ended up finding mine and just putting it back in the correct position. I found a picture that shows the piece and where the magnet would be.

[lechCe]

I have checked the fuse, it was not the issue.
Regarding the magnet, I think it is the electro sensor, that finds out when the pistol is in and opens the circuit in the bleeding valve. I thought that pushing the plastic tab will be the manual way to open the circuit.

Is there a way to check the sensor?

How about removing completely the bleeding valve and just joining two pipes that are attached to the valve

[mipstien]

Originally Posted by lechCe

I have checked the fuse, it was not the issue.
Regarding the magnet, I think it is the electro sensor, that finds out when the pistol is in and opens the circuit in the bleeding valve. I thought that pushing the plastic tab will be the manual way to open the circuit.

Is there a way to check the sensor?

How about removing completely the bleeding valve and just joining two pipes that are attached to the valve

I could not manually bypass anything. I don't remember why. YMMV

Try using another magnet and put it in or around the neck and listen for the other magnet click.

If I recall the reason for that magnet is to seal off the tank and when activated the magnet gives the air in the tank an escape route during filling. Otherwise the tank would spill fuel in a hard turn. The tank is under pressure because the fuel filler neck is closer to parallel with the ground and would let fuel come back out if it wasn't pressurized. This is why the tank makes a sucking sound when opening the fuel cap sometimes.

I was chasing a whistling sound that was caused by a vacuum leak and managed to dislodge the magnet during that inspection. The magnet is just laying between the plastic piece and the filler neck. When you remove the plastic piece or just moving it around the magnet is small enough to fall out. It really has nothing forcing it to be there when it's removed. It just happens to be captive when everything is put together. I can not recall the exact size of the magnet but I think it was a rectangle and about 3/4th to 1 inch. Roughly around 1.5 to 2.5 centimeters.

It could just be a bad vacuum line somewhere not allowing the tank to vent.

[mipstien]

When my magnet was missing it was hard to start after refilling and took a long time to fill.

This is a lot of good information.
https://www.pelicanparts.com/techarticles/Porsche-996-997-Carrera/106-FUEL-Replacing_Your_Fuel_Line_Vent_Valve/106-FUEL-Replacing_Your_Fuel_Line_Vent_Valve.htm

[10/10ths]

This happened to me.

It’s the “purge valve” on top of the tank, under the battery. It is a pain to get to. BUT, it can be done. Took me about an hour.

That part is #21 I believe.

[robdelorenzo]

Great info. Thanks. I don’t have the “whistling sound” problem. But, it has been been getting progressively more and more difficult to fill the tank. The amount of time until the pump shuts off has been getting shorter and shorter, even with the nozzle inverted. It’s an 02 base. A new fuel pump was put in about a year ago by a very knowledgeable indie, somI don’t think it’s the “lines into the fuel tank fix” (I seem to recall tha only applies <2000 Boxsters) So what do I try first? The valve at the neck of the tank? (about $200) the valve under the battery? How do I diagnose what’s failed/failing? Or do I throw parts at it next, starting with the least expensive (checking to see if the magnet/switch/thing has disconnected? You guys are invaluable! Thanks -

[10/10ths]

......the valve under the battery.

I tested it with air and put it under vacuum and it tested fine. But it was still bad.

I put a new one in and that is what fixed my “can’t fill the tank” problem.

Trust me. Just buy that valve, it’s not expensive, and replace it.

If that is NOT the problem (but it is) you will have eliminated a failure point and have a spare valve for the day it does fail.

But it IS that purge valve under the battery.

Let us know.

Good luck.

[robdelorenzo]

Thank you!
That will be this week’s project.
Soggy, gas soaked shoes need to become a distant memory.
Plus, that F150 with the two 25 gallon tanks that pulled in next to me has already filled both tanks and left.

I don’t know why I have never come across this before, but while researching the valve under the battery I found this:

997-201-944-00

https://www.pelicanparts.com/More_Info/99720194400OEM.htm?pn=997-201-944-00-OEM&bt=Y&fs=0&SVSVSI=986M

Don’t know if that will help or not, but it is the easiest (and least expensive way to start)

[losblancos]

Guys does anyone have any tips regarding this problem for a 987? The tank/vent design is different if I'm understanding these parts manuals correctly.

[JayG]

I just flip the nozzle upside down and it fills to full no problem