Fueling auto-off before full tank and then trouble starting after

I've had my Base Cayman for about a month now, and I've noticed that its hard for me to get a full tank with autofill. Most of the time it will trigger early and I'll find myself leaving the gas station with not a completely full tank. This itself isn't that concerning, but then I started to realize that my engine was also having trouble cranking over. I'm not sure if these are correlated or not, but I will try turning on my engine shortly after a drive tomorrow without messing with the fuel cap. I did see that one possibility for my issues is the fuel purge valve. I'm having a hard time finding a DIY or any info really for this for the 987. Can anyone confirm that this is the part number below? Does anyone know where this is located? It looks like 986s had similar symptoms but their issue was with a vent valve that was near the fuel cap (front passenger wheel well). And man, this purge valve is $500!? Older posts about it make it sound so much cheaper, so hopefully someone tells me I'm looking at the wrong part? 98711012801

I had a Hyundai with similar symptoms and the purge valve resolved the issue. I looked over the parts diagrams, and that does appear to be the correct part number.

Ah okay, thanks! I was hoping that it could possibly be something else before I drop $500 on a part that may or may not fix it. Sounds like I’m in the right direction though.

The refueling thing was a common 987.1 complaint. Mine likes to have the hose end of the nozzle lifted as far as possible with the nozzle inserted fully. Been that way from new. Recall that others have had luck inserting the nozzle upside down. I've also heard that some have luck with a collar designed to work with vapor recovery nozzles. Might want to try these kind of things before digging deeper. As to slow crank how old is the battery?

Ah, good to know. I did check my battery today and it looks like its 8 years old. Might as well change it first before committing to the $500 purge solenoid. Would it make more sense that the battery would have more issue with a warm car vs a cold start?

8 years old! You have definitely gotten a full life out of that one. I'm surprised it has lasted this long. Regardless of your starting issue, I would replace that battery before it strands you somewhere.

Regarding the fueling issue. I have experienced this on other cars and have found the problem to be caused by people that insist on filling gas to the very top of the neck, they keep clicking the pump until the they can almost see the gas. Problem with doing that is in almost all cars there is a vent near the top of the filler neck that runs down to the charcoal filter and purge valve (emissions parts) These parts were never intended to deal with strait gas only gas vapours. If the tank is always filled to the very top a small amount of fuel will drain down the emission parts and destroy them prematurely. Its in your owners manual that most dont read stating to stop filling fuel tank when it clicks off once and slow the fill rate s its getting near the top. This info is not just to keep yourself from over filling the tank. worth mentioning is as I will surely get asked why gas does not enter the vent on regular feeling and reason is because the vent is high enough that the pump tube is long enough it will bypass that when inserted.

I had this issue with both my Cayman and Boxster . The problem with both of mine was the Leak Detection Pump/ Canister. These have been known to go bad (according to my mechanic) Overfilling will shorten the life of the pump/ canister. It's about a $600 repair at an indy shop. My Boxster was still new when this happened. It also makes the car hard to start after the fill up when failing.

What you say is true. I've observed the behavior myself. Not sure what they expect the extra cup of gas to get them. What I'm talking about is entirely different. I can put the nozzle in fully with a quarter tank, let it hang, start it and have it click off almost immediately. Filling the tank a half gallon at a time is not on. Lift the hose end, start it and it clicks off at full. Been that way from new. No start problems though. There was a long thread or two about this with many complaining of the same thing back in the 2006 - 2008 time frame. And yes, I'm too lazy to search for it now. Seem to recall there are codes for errors in the vapor recovery system. Have you checked?

Yes exactly, my problem with the fill up itself is similar to yours where it essentially prematurely clicks off before the tank is actually full. The car is pretty new to me so I have yet to get diagnostic equipment, but sounds like I should be getting something like the durametric soon.

In the interim Autozone and probably others will download fault codes for you. Used to be free. Should at least get the standard OBD II codes if not Porsche specific. I use Durametric FWIW. Next fill up you might try my solution. No cost other than having to hold the nozzle. Might separate out whether one issue or two.

Yea definitely, I'll give it a shot, no harm besides people looking at me and wondering why I'm holding the nozzle!

I hold the nozzle upside down when filling up, this seems to help as well.

There is a Porsche TSB regarding some of this problem. A small plastic ring is attached to the filler neck. Back when my car was new, it solved the problem completely. Tim

I’ve got an 05 955 Cayenne and I have the identical issue. My fuel gauge never goes above 3/4 tank and always has hiccups for 30 seconds after starting. I replaced fuel cap originality as that was what the code read but still persists. At first I thought it was the accelerator but when I tried to pump it it would go crazy so I’ve learned not to touch it and crack it and then it idles out.

Thanks everyone! I did the angling of the pump today and it seemed to do the trick! I had done a battery change earlier in the week and the car started up fine. Looks like it was two problems in one. Not sure why the hot/warm start would make the battery weaker but we're all good.