C5 gas gage problems
Thread Starter
6th Gear
Joined: Jun 2010
Posts: 6
Likes: 0
From: Huntington Beach CA
C5 gas gage problems
I have a 2002 C5 with the typical gas gage problem and have used the sea foam and techron additives to the gas tank and has not fixed the problem. Any suggestions? 
Burning Brakes
Joined: Nov 2007
Posts: 951
Likes: 2
From: Rochester MN
Read the codes out of the DIC (dash) and determine which side it is... It costs about $350 to replace the right side and about $100 to do the left side... That's for parts if you go with genuine GM parts..
It's my understand either side is not all that bad to replace.. My right side is acting up but right now it's working but I suspect it has not 'healed'...
It's my understand either side is not all that bad to replace.. My right side is acting up but right now it's working but I suspect it has not 'healed'...
Le Mans Master
Joined: Jan 2004
Posts: 9,488
Likes: 1,743
From: Knoxville Tn
Maybe it's just me, but it seems like we're seeing more and more of this problem lately....I suspect the quality of our gasoline is declining rapidly or it's just the aging factor of the C-5. Eithr way, it sucks.
BTW. try adding the tehcron when the tank is 1/2 full let it sit over night, then give yourself a fillup. It might just work..
BTW. try adding the tehcron when the tank is 1/2 full let it sit over night, then give yourself a fillup. It might just work..
Advanced
Joined: Sep 2006
Posts: 96
Likes: 0
From: Richmond Virginia
I know it's going to sound blasphemous, but I had (at least one of) the gauge issue (showing empty from 7/8 > 1/2) and tried seafoam and techron and chevron-only gas. After a few months it showed almost zero difference. Filled up once at a shell station and the gauge has worked fine ever since (3 tanks so far I think).
Race Director
Joined: Aug 1999
Posts: 11,114
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From: SE Pennsylvania
St. Jude Donor '03 thru '26
Oldtimer
Gas quality ?
Maybe it's just me, but it seems like we're seeing more and more of this problem lately....I suspect the quality of our gasoline is declining rapidly or it's just the aging factor of the C-5. Eithr way, it sucks.
BTW. try adding the tehcron when the tank is 1/2 full let it sit over night, then give yourself a fillup. It might just work..
BTW. try adding the tehcron when the tank is 1/2 full let it sit over night, then give yourself a fillup. It might just work..
Le Mans Master
Joined: Mar 2009
Posts: 5,280
Likes: 1
From: PALM COAST Flordia
Gasoline quality is steadly declining. And if that wasn't bad enough, the amount of ethanol the EPA wants in each gallon to rise it's % in pump gas everywhere. And ethanol, or alcohol has a very corrosive effect on all those tiny little metal parts in your fuel system, the pump and then there's the fuel pressure regulator and the fuel injectors. All things being equal, ethanol means rust, more ethanol more rust and corrosion. you can't fight the government. Just the facts of life.
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Burning Brakes
Joined: May 2010
Posts: 1,167
Likes: 2
From: Pittsburgh Pa
I've built several boosted high hp cars that ran on E85...the longest was for 3 years. Opening the tank at the end there was NO visible issue anywhere. Seals in the fuel pump, connectors, tank lining...nothing. This was on vehicles a lot older than c5's as well. Ethanol isn't corrosive. On some microscopic level, I'm sure there's evidence, but in the real world I just never saw any such thing. Internally the engines were clean as hell...that was the only difference I saw. Ethanol isn't like Methanol...meth will eat your stuff alive...and make you blind if you drink it. Two different forms of alchohol due to still technique.
On the gas gauge thing...my Z is doin it as well. I just added techron and cleared the code from PCM through the DIC. Workin for now.
On the gas gauge thing...my Z is doin it as well. I just added techron and cleared the code from PCM through the DIC. Workin for now.
Racer
Joined: Mar 2011
Posts: 337
Likes: 1
From: Mechanicsville Md
Had the same issue with my 2002 coupe. At 3/4 it went to zero, filled it up and it went to full. Road around and it got down to 1/2 and then went to zero. I got the techron in it now and filled it up with shell gas. It got all the way to 1/4 and I added another bottle of techron and shell gas and problem seems to has been fixed. You need to run the tank down to 1/4 or less. Eventhough the gage may not work the float is still moving and it's rubing against the coper pickups. Put the techron in and fill it up and it should get better. If not then you may need to change the sending unit. Driving very easy you should get about 350 to 400 miles to a tank. l it up and reset the trip odometer. Good luck
Last edited by Jumper11; Mar 21, 2011 at 08:39 PM.
Melting Slicks
Joined: Jun 2008
Posts: 2,283
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From: Katy Tx
I had the typical 3/4 tank gauge crash -- tried Techron a few times with no change but... I went out of town for a week so I filled the tank up and added the Techron - when I returned the gauge started working! - seems like letting the Techron work for a while and with the fluid covering all of the coils on the sender , I think that cleaned them up.
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I'd give it a couple more tries with the Techron or SeaFoam. If it still doesn't work, you may have to replace the sending units.
Advanced
Joined: Oct 2009
Posts: 67
Likes: 1
From: Apple Valley CA
I have the same vexing problem in my 2002. I finally went to Auto Zone and bought one of the approximately $100 code readers and now when the gage drops to zero, the first time I pull over I plug in the reader and even though it shows "No Codes" I go through the process of clearing them. As soon as I turn the ignition back on the gage goes up to where it should be. Mine doesn't do it every time and can't be depended on to drop off on a schedule so I just carry the reader in the glove box and use it when necessary.
Jim
Jim
Safety Car
Joined: Dec 2002
Posts: 4,338
Likes: 66
From: Whittier California
I had this problem while I was using Chevron gas. The head mechanic at West Coast Corvettes recommended a switch to Mobil gas. After a couple of tank fulls of Mobil, the problem with the gas gauge went away. That was about six years ago. Hope this helps.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Had the same issue with my 2002 coupe. At 3/4 it went to zero, filled it up and it went to full. Road around and it got down to 1/2 and then went to zero. I got the techron in it now and filled it up with shell gas. It got all the way to 1/4 and I added another bottle of techron and shell gas and problem seems to has been fixed. You need to run the tank down to 1/4 or less. Eventhough the gage may not work the float is still moving and it's rubing against the coper pickups. Put the techron in and fill it up and it should get better. If not then you may need to change the sending unit. Driving very easy you should get about 350 to 400 miles to a tank. l it up and reset the trip odometer. Good luck
Exactly right and the way I have been telling everyone to do it. Adding it to a full tank is useless it will sit in the left tank.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
I have the same vexing problem in my 2002. I finally went to Auto Zone and bought one of the approximately $100 code readers and now when the gage drops to zero, the first time I pull over I plug in the reader and even though it shows "No Codes" I go through the process of clearing them. As soon as I turn the ignition back on the gage goes up to where it should be. Mine doesn't do it every time and can't be depended on to drop off on a schedule so I just carry the reader in the glove box and use it when necessary.
Jim
Jim
Melting Slicks
Joined: Jan 2007
Posts: 3,021
Likes: 133
From: Conejo Valley CA
Check out the corroded traces... the dark colored gunk. These traces should be as shiny as a brand new silver dollar,
Burning Brakes
Joined: May 2010
Posts: 1,167
Likes: 2
From: Pittsburgh Pa
I have the same vexing problem in my 2002. I finally went to Auto Zone and bought one of the approximately $100 code readers and now when the gage drops to zero, the first time I pull over I plug in the reader and even though it shows "No Codes" I go through the process of clearing them. As soon as I turn the ignition back on the gage goes up to where it should be. Mine doesn't do it every time and can't be depended on to drop off on a schedule so I just carry the reader in the glove box and use it when necessary.
Jim
Jim
And....I love being pariotic and all...but did you REALLY do that to the back of your vette....
Next time just hold the options button and press the fuel button 4 times in a row. It'll display the pcm code. Hold reset and it'll clear the code...no scanner needed.
