Fuel Guage Reads Empty
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Joined: Feb 2023
Posts: 93
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Fuel Guage Reads Empty
I've owned my C5 for 21/2 years. daily it 9-10 months of the year. Every 2-3 months the fuel guage would read inaccurate and I would go to the parts store and get Tecktron , dump it in the fuel tank and everything would be ok for 2-4 months. But I haven't had to add an additive for the last 6 months. Last Friday I was driving and the "Check Guages " light came on the guage cluster. Checked my guages and the fuel guage was reading empty, although I had filled up the tank the day before.
I'm going out to the parts store in a few minutes to get some tecktron, but if that doesn't work, I want to check with you guys as to my next steps or hear any experiences you all may have had with this issue.
Thanks
I'm going out to the parts store in a few minutes to get some tecktron, but if that doesn't work, I want to check with you guys as to my next steps or hear any experiences you all may have had with this issue.
Thanks
Drifting
Joined: Sep 2022
Posts: 1,373
Likes: 1,062
I've owned my C5 for 21/2 years. daily it 9-10 months of the year. Every 2-3 months the fuel guage would read inaccurate and I would go to the parts store and get Tecktron , dump it in the fuel tank and everything would be ok for 2-4 months. But I haven't had to add an additive for the last 6 months. Last Friday I was driving and the "Check Guages " light came on the guage cluster. Checked my guages and the fuel guage was reading empty, although I had filled up the tank the day before.
I'm going out to the parts store in a few minutes to get some tecktron, but if that doesn't work, I want to check with you guys as to my next steps or hear any experiences you all may have had with this issue.
Thanks
I'm going out to the parts store in a few minutes to get some tecktron, but if that doesn't work, I want to check with you guys as to my next steps or hear any experiences you all may have had with this issue.
Thanks
Drifting
Joined: Jul 2019
Posts: 1,977
Likes: 846
From: FL Keys
2025 C5 of the Year Finalist - Unmodified
There comes a time when the Techron trick no longer work. You seem to be there, time to replace the sender. Really is not that hard to do yourself. Some years are a little more challenging. I did mine “98” in less that 2 hrs. Good luck. 
Melting Slicks
Joined: Nov 2014
Posts: 3,399
Likes: 1,339
From: Havre de Grace Maryland
I have had this problem for several years. At first, Techron worked but then it did not no matter how much I put in. Now when I fill up, the gauge goes to empty until I hit a significant bump in the road and/or make several sharp turns then the gauge starts working again until the next fill-up. I decided to just live with this issue.
No Hostility Be Happy
Joined: Aug 2018
Posts: 10,061
Likes: 7,375
From: South Hill Wa
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
Working 100% of the time 60% of the time is not a fix lol. Techron is a half assed band aid when it comes to the senders.
If you have a 2003.5 or older car replacing the senders is not the scary monster that many just assume it is.
If you have a later C5 I'm sorry and I really do feel bad for you.
I think the trick these days is trying to find new OEM senders. I believe they are drying up. For years Rock Auto had them for around 50 bucks.
Also, if have the check gauges light coming on that is a sign that the car knows there is fuel sender faults and it will store codes for it that can help point you in the right direction.
Also if you happen to have HP tuners or another good bidirectional scanner tool you can see the fuel level sender voltages real time at all times and this will absolutely tell you which one or if both senders are acting up.
If you have a 2003.5 or older car replacing the senders is not the scary monster that many just assume it is.
If you have a later C5 I'm sorry and I really do feel bad for you.
I think the trick these days is trying to find new OEM senders. I believe they are drying up. For years Rock Auto had them for around 50 bucks.
Also, if have the check gauges light coming on that is a sign that the car knows there is fuel sender faults and it will store codes for it that can help point you in the right direction.
Also if you happen to have HP tuners or another good bidirectional scanner tool you can see the fuel level sender voltages real time at all times and this will absolutely tell you which one or if both senders are acting up.
Melting Slicks
Joined: Sep 2012
Posts: 2,217
Likes: 784
From: Fort Myers Beach Florida
On my first failure, it took less than two miles of driving for Techron to do its magic. A few years later it took multiple doses and almost 100 miles for the gauge to come back to life. Now I add Techron to the tank 3-4 times every year and it's all good. Gald I was patient and didn't tear into it.
No Hostility Be Happy
Joined: Aug 2018
Posts: 10,061
Likes: 7,375
From: South Hill Wa
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
On my first failure, it took less than two miles of driving for Techron to do its magic. A few years later it took multiple doses and almost 100 miles for the gauge to come back to life. Now I add Techron to the tank 3-4 times every year and it's all good. Gald I was patient and didn't tear into it.
You can have a fuel sender out of one of these cars in under a half hour. It's not as hard as people make it out to be (pre 04)
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Heel & Toe
Joined: May 2006
Posts: 20
Likes: 5
From: Chicago suburbs
If you get to the point where you are thinking of diving into the sender replacement job, do yourself a favor and make sure you have the correct reference voltage from the PCM to the rear of the car. I changed the senders and it didn't fix the problem.. In the end, the PCM was not putting out the correct voltage, so the gauge wouldn't work regardless of sender age. My PCM problem may have been an outlier, but checking it would be a logical first step after the Techron fails. My long-winded saga is here https://www.corvetteforum.com/forums...placement.html.
Z
Z
Last edited by zane8; Jun 24, 2025 at 02:53 PM.
Thread Starter
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Joined: Feb 2023
Posts: 93
Likes: 12
OK, much useful input. Thanks. So on my 98 , are there 1 or 2 sending units? If 2 I assume there is one in each tank. I'm guessing the tanks should be nearly empty of fuel before I start to remove the sending unit ( s )?
And also will I gain access to the sending units via the rear wheel openings after I remove the rear wheel ( s )?
I will look this up on YouTube videos, that has always been my main source for the C5 for info, usually.
And also will I gain access to the sending units via the rear wheel openings after I remove the rear wheel ( s )?
I will look this up on YouTube videos, that has always been my main source for the C5 for info, usually.
Heel & Toe
Joined: May 2006
Posts: 20
Likes: 5
From: Chicago suburbs
You have two sending units which can be accessed by the circular covers in the wheel wheels. The passenger side has just the level sender and the drivers side has a level sender and the fuel pump. Getting the drivers side out and back in is more tricky since there's a lot of stuff going in that hole - you have to maneuver both the pump and the sensor. You must ensure that the float arms on the sensors are free to move once inside the tank. Yes, you want the tanks as empty as possible. I drained the whole thing by pumping it out via the fuel rail.
Z
Z
Last edited by zane8; Jun 24, 2025 at 04:22 PM.
Melting Slicks
Joined: Sep 2012
Posts: 2,217
Likes: 784
From: Fort Myers Beach Florida
Personally I could not get one or both of the fuel senders out of my car in a half hour. I purchase Techron at the local auto store when they have a buy one get one free (BOGO) so it might cost $6-7/bottle. I may have spent $30-40 on Techron in my lifetime. Way cheaper than sending the car out for service and possibly ending up with aftermarket (Chinese) parts with questionable quality.
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Melting Slicks
Joined: Nov 2014
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From: Havre de Grace Maryland
Burning Brakes
Joined: Aug 2013
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From: Lehigh Valley PA
2022 C5 of the Year Finalist - Modified
Mine occasionally will go to empty while driving over an hour,, check engine light comes on. Then, it goes back to normal after 20 minutes or if I turn it off. Then the next time I start it, it's perfect!
Shhhhh!!!
Shhhhh!!!
Safety Car
Joined: Jan 2001
Posts: 4,995
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From: Hilton NY
Fuel sender problems for many brands of cars were caused by fuel companies putting sulphur in the gas, I think the class action lawsuits mostly ended that practice. You might try buying gas from a different company and see if that helps, the gas blend for the climate in your part of the country might also cause sender problems.
Drifting
Joined: Jul 2019
Posts: 1,977
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From: FL Keys
2025 C5 of the Year Finalist - Unmodified
I did this one time before replacing the sender. I removed the sender and took to the workbench, cleaned the crud off of the “wire element” with a pencil eraser and tiny screwdriver. Reinstalled and it worked for about 18 months longer. I was then lucky to find a new replacement, I believe I found it from RockAuto.
