When I drove my car from SF back to Phoenix I filled up in California 3 times. Each time after the pump automatically stopped, I instinctively tried to squeeze out a little more fuel into the tack. Bad idea - gas immediately overflowed.

Here in AZ, I ended up with the opposite problem. Pumps would always stop too soon, sometimes annoyingly so. So I would keep trying to put fuel into the car 10 to 15 seconds at a time, until guess what - it overflowed.

I've determined that my onboard computer is fairly accurate on its MPG. So now before every fillup I do an miles driven/MPG calculation based on the trip computer to determine how many gallons I KNOW for sure the tank will take. I then fill up to that amount, restarting the pump if it automatically stops, and add maybe another 1/4 gallon.

That process was working just fine for the longest time. Until I found a pump that behaved as described in my first paragraph, at which time fuel overflowed again when I gave that extra squeeze.

 

I will try this to see whether I can get the nozzle to shut off faster thereby alleviating the overflow. Either way, sounds like filling the TT is a more delicate process than the older 911s.

I will also ask the dealer about the venting on the tank, as it does act like it's not venting properly.

H_D

 

Hey all, I want to revive this old thread because I'm having the exact same issue on my new-to-me 996TT and there's not a lot of info on rectifying it. To recap, when I fill up with gas, the tank will always overfill and gas will gush out of the fuel filler neck without the pump shutting off. The tank fills completely from any level and everything appears to function normally except the pump does not click off. This happens with every pump I've used (and I've used dozens). I've tried inverting the pump handle without improvement. OP, did you find out what was wrong? Thanks in advance!

 

And revived it is...

That is the exact opposite of mine; I cannot get the fuel nozzle to fill without inverting it.

 

I was never able to figure out the problem, but I do know from personal experience that repeatedly overfilling the gas tank = $2400 bill to replace the gas tank.

 

Ooof. That's a chunk of money I'd rather spend elsewhere. Thank you for the heads up. I'll def make this fix a priority. And if anyone else has had (and resolved) this problem, please let me know.

Does anyone know if the TT has the same gas tank and fuel system components as the non-turbo models? Figure I'll ask in their forum if that's the case.

 

I’ve had the no shut off/gush problem from day one ownership. ~3.5 years.
no issue putting enough or false “full” shutoff.
I resigned myself to the “12 gallon from empty”technique, but interested in finding the solution.

 

I have to fill mine with in the inverted position or constantly restart it..

 

I find, if the gas pump is a slower one, it works fine in the non-inverted manner, but most pumps here in The Great White North pump pretty fast, thus inverted it is.

 

I found early on to just live with the shut off as being all there is. This is not unique to the 996tt, it is a big issue on my C7 Vette as well. Lots of posts on it over on the Corvette Forum.