fuel gauge issues
Thread Starter
3rd Gear
Joined: Dec 2011
Posts: 3
Likes: 0
From: Orlando FL
fuel gauge issues
I have a 97, I can fill the tank but the gas gauge only shows half a tank. I have tried two bottles of techron (not all at once) and still hasn't made any difference. The gas gauge will drop to empty, but it usually goes back to the previous level. It's been happening for a couple of months, that's about how long it took the techron to get totally through the system.
Drifting
Joined: May 2008
Posts: 1,695
Likes: 490
From: Denver, NC
There is lots of info on this. But I will share my personal experience. I purchased a used 2004, and a few months after buying, I started getting the gauge going to empty at fill up, then after about 5 miles it would start coming in, and be erratic, then eventually work. I was using Shell exclusively.
I used concentrated techron several times, and the gauge worked, then reverted.
I switched from the Shell station by my house to BP and used the Techron - car is now perfect. As an experiment I switched back to Shell for a while and the gauge problem popped back. Have been using BP with Techron on and off, and gauge has been perfect. In the beginning I used the concentrated cleaner back to back before the version I bought at Costco..
Costco sells 6 packs of Techron for like 15$ or something ridiculous. It is not the concentrated version - I add it every other tank or so. I was running it every tank at first, and am backing off to see what happens.
I was traveling for work for a while when it was happening, and I remember filling the tank with the Techron and BP and letting it sit full for several days. I could actually get the gauge to come in if I made a quick swerve - so I knew something good was happening. Now it's been perfect for nearly a year.
Just what I experienced.
I used concentrated techron several times, and the gauge worked, then reverted.
I switched from the Shell station by my house to BP and used the Techron - car is now perfect. As an experiment I switched back to Shell for a while and the gauge problem popped back. Have been using BP with Techron on and off, and gauge has been perfect. In the beginning I used the concentrated cleaner back to back before the version I bought at Costco..
Costco sells 6 packs of Techron for like 15$ or something ridiculous. It is not the concentrated version - I add it every other tank or so. I was running it every tank at first, and am backing off to see what happens.
I was traveling for work for a while when it was happening, and I remember filling the tank with the Techron and BP and letting it sit full for several days. I could actually get the gauge to come in if I made a quick swerve - so I knew something good was happening. Now it's been perfect for nearly a year.
Just what I experienced.
Last edited by Ed Ramberger; Feb 25, 2019 at 10:40 PM.
Safety Car
Joined: Jul 2010
Posts: 3,997
Likes: 386
From: Chandler AZ
On my 1999, the guage will go to full, but once in 2010 on a trip to Texas I ran out of gas in the middle of nowhere on I40, tank showed half.
Since then I have been paranoid to not get gas at 1/2 tank, fear of running out again.
For all I know techron concentrate has fixed it?
Once I was going to see how far it would go while carrying 2 gallons of gas in a can in the car, but decided not to.
I recommend the techron concentrate, not just the injector cleaner.
How many miles do you go between fill ups?
Since then I have been paranoid to not get gas at 1/2 tank, fear of running out again.
For all I know techron concentrate has fixed it?
Once I was going to see how far it would go while carrying 2 gallons of gas in a can in the car, but decided not to.
I recommend the techron concentrate, not just the injector cleaner.
How many miles do you go between fill ups?
Last edited by 1999corvettels1; Feb 25, 2019 at 11:37 PM.
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Team Owner
Joined: Jul 2016
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From: The Steel City, Colorful Colorado
Winner 2020 C7 of the Year - Modified
I have an 03' and am pretty sure I'm in the same situation as the 04'. 8Vette7 may chime in and set this straight as he is the guru on these issues.
Last edited by FX VETTE; Feb 26, 2019 at 01:12 PM.
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Racer
Joined: Mar 2011
Posts: 420
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From: West Deptford NJ
Let the gauge go to Reserve, then add the Techron and go enjoy a HPDE track day! I just deal with the gauge issue but this method has lasted the longest. I only have the gas gauge acting erratically on fill up. The gauge bounces up and down eventually stabilizing giving a correct reading. Shell gasoline also initiated the problem three years ago.
Last edited by jlaw1313@comcast.net; Feb 26, 2019 at 10:27 PM.
Melting Slicks
Joined: Dec 2004
Posts: 2,847
Likes: 1,144
From: Sleepy Hollow- NJ
Best write up about the C5 fuel tanks, functionality and issues I've ever come across online.
https://www.z06vette.com/threads/how...m-works.60056/
https://www.z06vette.com/threads/how...m-works.60056/
Pro
Joined: Dec 2013
Posts: 627
Likes: 181
From: west coast of Canada
I copied this post a while back, hope this helpsFuel gauge issues are a VERY common issue with the C5 fuel system. The sensors (one in each tank) are prone to oxidation that causes the gauge to go crazy and often drop to empty (the default gauge level). Because there are 2 tanks on the C5 and one sensor in each tank, the computer calculates the amount of gas left in the car to display on the gauge. Further since the passenger side tank is emptied first the computer expects to see the level in the passenger tank decrease BEFORE the level in the driver’s side tank. If that does not happen because oxidation on one or both of the fuel level sensors, there are one or more PCM codes set.
If you pull and post your codes you can determine which of the
sensor(s) are experiencing the problem. You can also treat the fuel to attempt to dissolve the oxidation to avoid future gauge issues. Get yourself a couple of large bottles of Techron Concentrate Plus from a parts store (20oz bottles). With the tanks down to 1/3 of a tank (2/3rd's empty) add the entire 20 oz bottle and then fill the tanks with your favorite prem fuel. Since the driver’s side tank is filled first the churn of gas added mixes the Techron and fuel and once the drivers tank is filled the mixed fuel flows over the crossover tube to the passenger tank insuring that the fuel and additive reach both tanks. It often takes more than one treatment to dissolve the oxidation. If you can let the car sit for a few days the additive will have a better chance to do its job.
If the treatments do not cure the problem then you are looking at replacement of the offending sensor(s). If your car has an early build date (before Late October 2002) you will have the old style fuel tanks and replacing the sensors is pretty easy as there are access panels on the bottom back side of the fuel tanks that provide access to the pump and sensors. If your car has a late 2002 build date or a 2003 build date the car will have the FFS fuel tank system.. Replacing the sensors in the FFS system is a BIG job as the tanks must be dropped to gain access to the pump and sensors.........
The sulfur build up can cause bad input to the computer and the gas gauge then "defaults" to zero. A turn off and restart restores things. GM came up with a PCM update (reflash) way back when which fixes the problem. It used to happen to me all the time before the reflash was done; tried different gasolines, Techron, etc., but only the update fixed it - and permanently.
It's been a long time (at least 10 years) since mine was done, but a Google search should find the info for you.
SeaFoam is another additive that folks have had success with
Also use Shell V power gas.
Can take multiple treatments to correct.
If you pull and post your codes you can determine which of the
sensor(s) are experiencing the problem. You can also treat the fuel to attempt to dissolve the oxidation to avoid future gauge issues. Get yourself a couple of large bottles of Techron Concentrate Plus from a parts store (20oz bottles). With the tanks down to 1/3 of a tank (2/3rd's empty) add the entire 20 oz bottle and then fill the tanks with your favorite prem fuel. Since the driver’s side tank is filled first the churn of gas added mixes the Techron and fuel and once the drivers tank is filled the mixed fuel flows over the crossover tube to the passenger tank insuring that the fuel and additive reach both tanks. It often takes more than one treatment to dissolve the oxidation. If you can let the car sit for a few days the additive will have a better chance to do its job.
If the treatments do not cure the problem then you are looking at replacement of the offending sensor(s). If your car has an early build date (before Late October 2002) you will have the old style fuel tanks and replacing the sensors is pretty easy as there are access panels on the bottom back side of the fuel tanks that provide access to the pump and sensors. If your car has a late 2002 build date or a 2003 build date the car will have the FFS fuel tank system.. Replacing the sensors in the FFS system is a BIG job as the tanks must be dropped to gain access to the pump and sensors.........
The sulfur build up can cause bad input to the computer and the gas gauge then "defaults" to zero. A turn off and restart restores things. GM came up with a PCM update (reflash) way back when which fixes the problem. It used to happen to me all the time before the reflash was done; tried different gasolines, Techron, etc., but only the update fixed it - and permanently.
It's been a long time (at least 10 years) since mine was done, but a Google search should find the info for you.
SeaFoam is another additive that folks have had success with
Also use Shell V power gas.
Can take multiple treatments to correct.