back from the dead!

anyway, i have a question about the fuel gauge reading. i was on the indicator light, 50 miles to empty. so i put in about 7 gallons (which cost me an arm+leg here in Cali) and my gauge didnt move, light didnt go away. i searched and read about the "hump" i believe in this thread or a different one with the gas tank plunger/level thing. but with 7 gallons, that should fill up enough to read accurately right?

i can generally fill the tank fine, but its the reading. im gunna go top it off and see if its reads accurately. but just wondering...

 

9 o'clock position for the handle works for me in terms of filling up. I've heard that only the first half of the tank is actually measured. The second half is estimated based on mpg and driving. Seems like a silly design to me, but if it's true, it could just be that you're not filling it up enough to get a real measurement yet. Let us know if filling it all the way up fixes the problem.

I certainly know your pain about the gas prices.

 

I've had the gas filling issue with my C4S and my turbo exactly the same. Fills to 3/4 and stops. I just put in the nozzle and let it go. When it stops I pull up on the nozzle slightly and restart the filling. It then will auto shut off when it is all the way full. This trick worked on both Porsches. My other trick is to go to a certain Chevron station and I can fill it like normal without any goofy "gymnastics" tricks

 

went to the gas station after i left my buddies shop that day, finished filling up, and ALL my gas showed up. its weird, i thought the plunger device was stuck or broken or something. even my "miles til empty" stayed the same with only 6-7 gallons. but once i filled it up, it was all there...

 

Actually, I think this makes sense if it's true that the sensor only measures the top half of the tank. That would mean that the car doesn't even know you put gas into the tank until you've filled it up past a certain point. When you first filled up the 7 gallons, it didn't register at all. Then, when you filled it up all the way, the car was able to read the amount of gas in the tank and reflect it properly on the gauge. Can anyone confirm whether this is the way the gas gauge works?

 

This is interesting I've only fueled up all the way a few times but it seemed to register a full tank on the gauge...never used the 9 oclock gotta try that one...

I ussually put in like 30-40 bucks during a quick stop here and there...ideally 3/4 to half tank is good, less weight in the car and keeps recycling more % of fresh fuel thru the system, and leaves some extra room for if you ever run thru a race fuel stop you have the option of mixing in maybe 2 - 3 gallons

 

Sounds like everyone is experiencing a similar problem. I have found this problem on my 2012 Turbo S, and other cars.

For years, I have been turning the nozzle upside down in order to add an additional gallon+/-. However, I once ended up ‘overfilling’ the tank, and in doing so Spilling a small amount of fuel & caused a CEL due to the excess gas draining into or affecting the Evap Canister. There is a small drain tube inside of the fuel compartment to drain excess fuel if you overfill the tank, however, the overflow/excess fuel can run the risk of having that fuel drain into the Evap Canister and/or disturbing the Recirc Valve, which will potentially cause a CEL due to a ‘false/positive’ Emissions EVAP failure. Usually, you’ll only get this message if you’ve forgotten to re-tighten the Fuel Cap correctly, and/or forgot to put the Fuel Cap back on. [Error Code PO455 if you have an OBDII ‘Reader’]

I have discovered that the some of the PN’s for this system have been changed by Porsche. This ‘fooled’ a mechanic @ a Porsche Dealership into initially advising me that Porsche no longer makes the Charcoal Evap Cannister. [Some research determined it was simply a new PN.]. A more experienced Tech Rep advised me that in order for the EVAP system recirc vavle to potentially reset and/or ‘check itself’, you must be less than 1/2 tank fuel. If the Recirc Ven Control Valve is successful in resetting, you may still need to go to a Dealer in order for the CEL to be ‘correctly’ reset, even though you could also get rid of the CEL with a Diametrics or similar OBDII device

My suggestion, after creating this problem by over-filling once too many times, is be mindful that you could induce a ‘self imposed’ CEL for all of the reasons stated above. Still, it is frustrating if you really want to fill the tank completely.