Gas gauge malfunction??
Thread Starter
Drifting
Joined: Apr 2008
Posts: 1,335
Likes: 0
From: Qualicum Beach British Columbia
Gas gauge malfunction??
First of all I have a 2002 C5 with 31,000km ( about 20,000 miles ) I have noticed on the last 4 tank fulls that the gas gauge seems accurate until I reach about 1/3 of a tank then.......................EMPTY!
When I fill the tank from that point it varies as to how much gas it will take.
I know of gas gauge problems with these cars but I am not familiar with these particular symtoms.
Any insight??
When I fill the tank from that point it varies as to how much gas it will take.
I know of gas gauge problems with these cars but I am not familiar with these particular symtoms.
Any insight??
Melting Slicks
Joined: Jan 2007
Posts: 3,021
Likes: 133
From: Conejo Valley CA
First of all I have a 2002 C5 with 31,000km ( about 20,000 miles ) I have noticed on the last 4 tank fulls that the gas gauge seems accurate until I reach about 1/3 of a tank then.......................EMPTY!
When I fill the tank from that point it varies as to how much gas it will take.
I know of gas gauge problems with these cars but I am not familiar with these particular symtoms.
Any insight??
When I fill the tank from that point it varies as to how much gas it will take.
I know of gas gauge problems with these cars but I am not familiar with these particular symtoms.
Any insight??
Plenty of insight here my friend....
This problem is caused by corroded fuel sensors that are part of the fuel sending unit assemblies. The C5 has two gas tanks so there are a total of two fuel sending unit assemblies. The fuel sensor part is an electrical arm that goes against a contact. The position of the arm is modulated by the fuel level in the tank. Incidently, GM does have a TSB (Technical Service Bulletin) on this.
Many people here will state that adding Sea Foam and Techron abates this problem. I have always been doubtful of this claim as it never worked for me. I ultimately replaced my fuel sending units and the problem went away.
I have a nice picture of the corroded fuel sensor... when I find it, I will be back and post it here.
Matt
PS: I've been in Victoria, BC this week on a business trip. Nice place... don't know it that's near you. Headed back to LA tomorrow.
Drifting
Joined: Feb 2008
Posts: 1,617
Likes: 2
From: San Diego California
I had the gas gauge problem myself. Even on a full tank it never went past the half way mark. Started using Chevron Supreme with techron and added only one bottle of techron - my gas guage has been operating normally for a year now
Racer
Joined: Mar 2007
Posts: 422
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From: California
I strongly recommend you give that attention ASAP. I had the same type of issue with my vette not too long after I got it, and it led to the one time I've owned my car leaving me stranded. 
Basically, something happened where I ran it too low with fuel (the sending units are cooled by fuel?), and the fuel sending unit fried or something. (car wouldn't start- no gas sent to motor) I had them replaced and its been fine ever since. Dont get stuck!! Take care of this before it has a chance do the same to you. Goodluck -Anthony
Basically, something happened where I ran it too low with fuel (the sending units are cooled by fuel?), and the fuel sending unit fried or something. (car wouldn't start- no gas sent to motor) I had them replaced and its been fine ever since. Dont get stuck!! Take care of this before it has a chance do the same to you. Goodluck -Anthony
Race Director
Joined: Aug 2001
Posts: 10,783
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From: Hurricane Alley
As others said, use a bottle of Techron or Seafoam and that should fix the problem. If you replace them then its just going to happen again eventually and its very expensive to replace them. 
Thread Starter
Drifting
Joined: Apr 2008
Posts: 1,335
Likes: 0
From: Qualicum Beach British Columbia
I will try the seafoam thing and see if it helps
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Racer
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From: Central NJ
St. Jude Donor '10
Iv had the same problem for a year. It happened 3 days after I purchased my car. Even after buying an extended warranty the dealer refused to fix it and was going to charge me over a thousand dollars to fix. I returned the warranty after 4 days of having it. Mine starts off a quarter low after a full fill and only after I fill does it fluctuate. Sometimes it will go to E and say I have no fuel. But it comes back up after a little driving. Id rather spend the thousand on fun stuff so I just set my trip meter after a fill 
Pro
Joined: Mar 2009
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From: Killarny MB
Mine use to drop to E around a third of a tank last year, did a couple cans of Seafoam and it worked normally a couple tanks after that. Now, it will just reads E after I start it, and it does not matter where the level is, however, it does come back to read the fuel level (or sometimes half the fuel level) after 5 minutes of driving. There are fixes on the forum that do not cost an arm and a leg, however, you have to be mechanically inclined to do the repairs yourself.
Race Director
Joined: May 2005
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From: Middletown, DE
It seems timing is of the essence for you -- the Techron fix worked for me and a number of other posters so no reason to be skeptical. But, it does not work for everybody and the most likely reason is once the corrosion goes too far no amount of additives will fix the senders.
So do the Techron RIGHT NOW and do it for 3 tankfuls. It's a cheap experiment. If that does not work, you have the choice of using your trip odometer or replacing the senders...
So do the Techron RIGHT NOW and do it for 3 tankfuls. It's a cheap experiment. If that does not work, you have the choice of using your trip odometer or replacing the senders...
Pro
Joined: Jan 2008
Posts: 549
Likes: 44
From: Houston TX
My gas guage only malfunctions after filling the tank. It goes to "E" and stays there for about 10 minutes. Then it pops up to usually around 3/4 tank and very, very slowly creeps towards "F". It'll then drop suddenly back down to "E" and stay there for a few minutes. When it pops back up it'll go to a slightly higher position than before. It goes back and for like this for the next 30 minutes or so until it finally reaches the correct position at or near "F".
I buy nothing but Chevron, and I have tried multiple bottles of Techron with no improvement. I'm currently trying a couple cans of Seafoam, and although it's helped a little after the first can, the problem still exists.
It seems like it's a hit or miss when it comes to using bottles of Techron or Seafoam to cure gas guage woes. I agree with Argent C5, in that it's probably related to how badly the sensors are corroded.
I buy nothing but Chevron, and I have tried multiple bottles of Techron with no improvement. I'm currently trying a couple cans of Seafoam, and although it's helped a little after the first can, the problem still exists.
It seems like it's a hit or miss when it comes to using bottles of Techron or Seafoam to cure gas guage woes. I agree with Argent C5, in that it's probably related to how badly the sensors are corroded.
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It seems timing is of the essence for you -- the Techron fix worked for me and a number of other posters so no reason to be skeptical. But, it does not work for everybody and the most likely reason is once the corrosion goes too far no amount of additives will fix the senders.
So do the Techron RIGHT NOW and do it for 3 tankfuls. It's a cheap experiment. If that does not work, you have the choice of using your trip odometer or replacing the senders...
So do the Techron RIGHT NOW and do it for 3 tankfuls. It's a cheap experiment. If that does not work, you have the choice of using your trip odometer or replacing the senders...
Hopefully the Techron will do the job for you - replacing the sending units is not cheap.
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