C6 gas guage issue

Same issue happened to my C5 last year as soon as I took it out of storage. It used to read right when i'd fill it up but when it reached about 3/8 of a tank it would drop to empty. I ordered the Techron and with as little fuel in the tank as i could (about 1/4 tank, maybe a little less) I put in a bottle then filled it up. I guess the Techron gets rid of the gunk from the fuel that builds up on the sending unit over time. Once it was cleaned off, I was good to go. I added a second bottle on the next fuel up and I have been good since. I will add another bottle after I get my first tank of fuel burned over the next while (if the weather would only cooperate here).

Fuel pump sending unit is about $200 but the installation might be considerably more, depending on wether or not you can access it without having to drop the tank.

Edit: a google search just came up with this 'This problem also occurs with early C6s, but to replace the unit on a C6 (and late-2003 to 2004 C5s) requires the removal of the whole rear drivetrain cradle to get access to the tank and fuel pump assembly."
 
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Same issue happened to my C5 last year as soon as I took it out of storage. It used to read right when i'd fill it up but when it reached about 3/8 of a tank it would drop to empty. I ordered the Techron and with as little fuel in the tank as i could (about 1/4 tank, maybe a little less) I put in a bottle then filled it up. I guess the Techron gets rid of the gunk from the fuel that builds up on the sending unit over time. Once it was cleaned off, I was good to go. I added a second bottle on the next fuel up and I have been good since. I will add another bottle after I get my first tank of fuel burned over the next while (if the weather would only cooperate here).

Fuel pump sending unit is about $200 but the installation might be considerably more, depending on wether or not you can access it without having to drop the tank.

Edit: a google search just came up with this 'This problem also occurs with early C6s, but to replace the unit on a C6 (and late-2003 to 2004 C5s) requires the removal of the whole rear drivetrain cradle to get access to the tank and fuel pump assembly."
Thank you for your reply. Great info.
 
One Techron so far did not work. Hmm Seafoam next. Fingers crossed.
Apparently you can run the car on Seafoam. Not sure I'd do that, but it's cheaper so do it several times if needed. I had to replace the carb on my go-kart because of the ethanol in gas, but once I started using seafoam in every tank the thing runs like a charm as do my tractors.
Hope you get it straightened out!
 
Could the Low fuel /Service fuel issue cause the Service Engine light to come on? Cause now my service engine light has come on. Car runs great only 72,000kms.
Sorry, can't tell you without knowing what the code is. You need to get an OBD2 reader to tell what it's reporting.
 
Could the Low fuel /Service fuel issue cause the Service Engine light to come on? Cause now my service engine light has come on. Car runs great only 72,000kms.
Possible for sure. I don't recall if my CEL was on when I had the Issue last year.
 
Apparently you can run the car on Seafoam. Not sure I'd do that, but it's cheaper so do it several times if needed. I had to replace the carb on my go-kart because of the ethanol in gas, but once I started using seafoam in every tank the thing runs like a charm as do my tractors.
Hope you get it straightened out!
You can even get it in a 4 litre can . It’s one of the automotive products that isn’t snake oil .
 

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