Gas gauge
07-04-2018 | 09:12 PM
#1
Thread Starter
Rennlist Member
Joined: Aug 2002
Posts: 349
Likes: 43
From: Calabasas, Ca, Scottsdale AZ
Gas gauge
Having an issue with my gas gauge. When I fill the car up, it only indicates under a half tank. The next time I shut the car off, and start it, the gauge indicates empty. Ive disconnected the battery, and nothing happened. Any ideas? Thank you
07-04-2018 | 10:40 PM
#2
Three Wheelin'
Joined: Mar 2009
Posts: 1,722
Likes: 73
From: Napa Valley, CA
I’m gonna try a guess based on my experience. I beleive that the gas gauge is related somehow to the battery/ecu. My battery was low after and after not driving the car for a couple weeks when I started the car the gauge would not register, even after filling the tank. (The clock also reset after starting.). I had access to a battery power pack (one of those units that you plug in and when you have a dead battery you unplug it, hook the cables to the battery/ground, and start the car), and when I used it the car started fine, gauges registered and clock kept time. I don’t know if this is your problem, but apparently a low battery can impact what your gas gauge reads, even after the car is started, so it must be an initial lack of power either directly impacting the gauges or causing the ecu to hiccup. Hopefully, your battery is low on juice (one way to test the theory would be to jump start your car and see if your gas gauge reads true); That is a simple and direct fix. Otherwise, it could take a better detective than me to figure it out. Best of luck.
07-05-2018 | 03:32 PM
#4
Rocky Mountain High
Rennlist Member
Rennlist Member
Joined: Aug 2007
Posts: 17,684
Likes: 1,590
From: Colorado
Is the car all-wheel drive (C4 or a C4S)? When you fill the car and the gauge indicates 1/2 full, do you think the tank is actually full and the gauge is wrong, or do you think the tank is only 1/2 full?
I ask because I believe the 996 AWD cars and 997 AWD cars share a fuel tank design. It's essentially a "saddle" design that sits over the front differential. There have been many reported issues with fueling where the gas pump shuts off and will not pump any more fuel into the tank, but the tank is only full on one half of the saddle. As I recall, the gauge reads from one side of the tank, so it's possible that you could have fuel in the tank but see an empty reading.
I have no idea if this is the case for you, but it might be worth investigating if you have an AWD car. I know that in my 996 C4S, there were some gas stations that caused this issue, and some that did not.
I ask because I believe the 996 AWD cars and 997 AWD cars share a fuel tank design. It's essentially a "saddle" design that sits over the front differential. There have been many reported issues with fueling where the gas pump shuts off and will not pump any more fuel into the tank, but the tank is only full on one half of the saddle. As I recall, the gauge reads from one side of the tank, so it's possible that you could have fuel in the tank but see an empty reading.
I have no idea if this is the case for you, but it might be worth investigating if you have an AWD car. I know that in my 996 C4S, there were some gas stations that caused this issue, and some that did not.