C5 Fuel Gauge Issues
 

Folks,

I have an 03 anniversary edition convertible. I purchased the car a few months ago. The car is a very low mileage example, 14 years old and only 6,000 miles on the odometer. Since I drive my corvettes I've started racking up the miles, which is bringing out some gremlins in the car. Sitting for most of the 14 years I expected to run into a few issues with the car when I stared putting the miles on. Thus far the lumbar support switches stopped working, took it to the dealer and was quoted $2,200 to fix, ahh no thanks. Today after driving for about an hour I stopped at a gas station for fuel. After fueling the car the fuel gauge dropped to empty and the low fuel light came on.... Strange! Drove it for about 20 more minutes, pulled over, shut the car off for a few minutes, started it back up, and the gas gauge worked! This is the second time it's done this after driving the vette for more than an hour. After the car sits for awhile the fuel gauge works fine. Anyone else have this happen to them? Any ideas what could of caused it? Something going out in the tank? Today was a standard hot Kansas day, high around 94. Could temp of caused this? Love to hear your guys/gals thoughts.

Thanks in advance!

This is a known problem with the C5. Sulfur build-up on the fuel sending unit can cause erroneous readings of the fuel gauge. Try using a bottle of Techron concentrate in your next few tanks of gas and see if the problem goes away. If not, you may have to dig deeper to find the source of the problem, which may include the sending units themselves. You can also pull the diagnostic codes off the DIC and post them up here to see what is indicated.

My car was particularly bad it took multiple treatments of Techron to fix but throughout the process I found that the car runs better with Techron in the tank any way.

I tried Techron in every other tank for a summer with no results. I filled up once with Shell V-Power premium and the gauge started to work. From then on it is the only gas I use and the gauge has worked fine ever since. I do add a bottle of Techron before I put it away for the winter.

:iagree:...from what I have seen, Techron concentrate dissolves the sulfer buildup on the cards...I use the stuff on a regular basis and use Exxon which has Techron in it...:flag:

---------
:iagree:

My experience too, although it only took a couple of treatments. I also switched to Shell Premium gas. No sticky fuel gauge and it runs great.

I have had the exact same problem that you describe. :ack:
I have also learned not to over fill the tank. It seems that trying to squeeze those last few drops of fuel into the filler neck increases my chance of repeating this problem. I also use techron about every third tank fill up. :thumbs:

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.

I checked the codes and I had a 1433. Sounds like what you guys are talking about. I'll pick up a bottle of the Techron and hope that corrects the problem. Thanks for the information!!

First time I've heard about this and sounds promising. Anyone else had this done? I have been having off and on problems with this for years. Usually solved temporarily with Techron, but seems to be happening more often now. Extremely annoying problem. (should have been a recall!) Luckily I have an early, pre FFS 2003 (I think) so I should probably just bite the bullet and replace the sensor

Mine's a very early '98, still with all the original parts in the fuel system - except for a new filter, and on the early cars the filters were in the fuel line, not in the tank, so no problem changing it.

Before the reflash, the gauge-to-zero issue would occur any time I took a longish run, usually about an hour or so in, IIRC.

Three years ago I was just about to take mine in to get the PCM re-flashed. Then I tried a tank of Shell V-Power gasoline. I had researched it and it has the most detergents and PEA. I have not had the gauge issue since. I only use Shell gas from that point on.
Changing the sensors may only be a temporary fix since build up on the new contacts will probably occur again. In my opinion the best fix is to keep them clean with good gas.

Yep me too, fuel gauge went to zero. 2001 C5
 

The happened this weekend of 6/23/2017 to 6/25/2017.
I have a 2001 Manual Convertible with about 25k miles. On 6/23 The car was on E so I filled the tank at a Mobil Station with 91 octane fuel. The fuel gauge went completely up to Full. The next day 6/24 I drove about 25 miles, stopped for about 3 hours, then about 20 miles later on my way back home I noticed the fuel gauge went to E. A couple miles later I stopped and cycled the ignition switch a couple time with no change. So I pulled over to a Chevron station and topped off the tank with 3.5 gallons of 91 octane fuel. Gauge still showed E. I went home, then read posts on CF (thanks all for the insight). On 6/25 I went on a 15 mile drive, stopping a couple times, and the gauge was still on E. My last stop before going home was at Autozone to buy Techron as suggested. I came back out to the car (before putting any Techron in) and fuel gauge was pegged at completely FULL. I recycled the ignition again then gauge went to 7/8 full which was more correct. I still added 10 OZ Techron once I got home. Hopefully this issue does not come back too often. These Corvettes do have some little issues that keep creeping up. Now that I have been in this car for 16 months and 4500 miles under my belt, I am hopeful that I have experienced most of these quirks and that there are not too many others that I do not know about.

I always use Chevron 91 (because it has Techron) and I also add several bottles of concentrated Techron fuel system additive over the course of a summers driving, and up to now it has mostly controlled the issue fairly well. This year it has become worse though so thinking the sensor may have to be changed. I'm going to try a tank of Shell V-Power first though as I haven't tried that. i think I will also look into that ECM flash which I didn't know about before this thread. Tip: Use your trip meter all the time in case your gauge screws up at random times. Actually, if it wasn't for the annoying "Check Gauges" light and "Low Fuel" warnings that annoyingly pop up I don't think I would bother replacing the sensor and just rely on the trip meter. PS I think your tank is supposed to be near empty when you put the concentrated Techron in. Just a heads up for the future.

Thank you to Forum Members!
 

Corvette Forum members - Thank you for taking the time to post your feedback on the fuel gauge issue. I have a 2004 C5 and have had this issue happen a few random times over the years. It just seemed to work out it's own issue. It's started happening again so I'm going to try the Techron and changing to Shell Gas to see if that helps. My journey with Nelly Bell my C-5 has been a continuous learning journey but the forum feedback has been invaluable in helping diagnose various issues and fixes. I still love my Vette!

Cat M

did you do a search on the forum? There are maybe thousands of posts on this issue.

maybe he does. Maybe he doesn’t. But you’ve proved you’re pretty smart here with that post. How does it feel? Good?

That is funny . When I used Shell gas my gauge started to act up. I now only use Sunoco 93.and never had the problem again