Car:
1998 Coupe, 85,XXX miles, 6MT.

This morning, when I was leaving the house, the fuel gauge suddenly crapped out on me. It was about 34 degrees outside, and I had just started the car. I got to the end of the driveway, and the gauge was on dead-empty, with the associated warnings. Range gave no reading at all.

This is the second time this has happened. I know it's an error because that evening on the way home (<30 miles ago) I filled the car. I have been filling it with Shell V-Power. This same thing also happened right after I filled up with V-Power for the first time. I pulled over and stopped the car, and on restart, it went back to working fine. I've filled up at least 15 times since then with the same shell gasoline (though sometimes with Exxon or BP mixed in), and and the problem didn't repeat. This morning, shutting the car down and restarting it did nothing to help; I even did it at lights two times on the way to work. Finally, at an underpass after about 15 miles of driving, it came back to life and has been fine since.

Is this something weird with Shell gasoline? I know they advertise putting all kinds of additives in their premium gas, but I buy it because it's close by and very cheap ($3.42/gal), and it's definitely not a no-name brand. Anyone had anything like this happen? (And to be clear, nothing but the fuel gauge sensor is affected; the car runs like a champ otherwise.

 

Find a special on "Chevron...Techron" concentrate and follow the directions. A couple of treatments should do the trick. Use more if necessary. This is a problem with almost all of our Vettes and the fix.

 

The problem you are experiencing is a known problem with C5's. Basically, the electrical contacts on the circuit board, where the fuel level information is modulated from mechanical (via a float in the tanks) to electrical information, gets deposits on it which deteriorate the integrity of the circuit board traces. Eventually, the deposits become so bad, the gas gauge will not get correct information at all. Many on here have recommended Techron additive and Seafoam additive.... and they swear by it. However, my opinion is that these additives won't reverse the problem but do prevent further damage (some will argue with me on this). The ultimate way to fix this is to have the fuel sending assemblies removed from the tanks and replaced. THEN, only use Chevron gas. That's what I did and my gauges work great ever since.

I should note that GM has a TSB (Technical Service Bulletin) out on this and the dealer service can do tests to determine if both or only one fuel sending unit needs to be replaced.

 

Great advice so far

As the guys say, it's a known problem on the C5 and it's a design issue. The fuels senders (one in each tank) become contaminated with sulfur and it prevents the electrical signal from being sent to the computer. You can see from this picture how delicate the pick offs are. I've also seen pictures where the pick offs become contaminated so badly that they are damaged. At that stage it's too late to fix and they have to be replaced.



The good news is you're doing everything right so far. Sounds like you caught the problem early so the sender should clean up. Keep the tank topped off - which you're doing - so the sender is always submerged. The only time I've had the problem is when I let the tank run low. Shell V Power has an additive similar to Techron which cleans the fuel system so its not a Shell gas problem but rotating gas brands helps as each additive is slightly different. Chevron has Techron as standard but try a few bottles of Techron anyway to give a concentrated treatment. Techron is formulated to clean up sulfur deposits so its worth a try.

Check the codes to see if you have any fuel related problems. If you have a fuel history code, clear it down and it may help.

There was a TSB for a PCM reflash and I'll see if I can find a link. That said, it costs $$ and it's had mixed reviews as to whether it works. Its worth giving Techron a try first.

 

Found it but it doesn't apply to your 98

Erratic Fuel Gauge Reading (Reprogram the PCM) #02-06-04-010A - (06/27/2003)
Erratic Fuel Gauge Reading (Reprogram the PCM)
1999-2002 Chevrolet Corvette
This bulletin is being revised to add models and update the Correction and Warranty Information. Please discard Corporate Bulletin Number 02-06-04-010 (Section 06- Engine).
Condition
Some owners may comment about the fuel gauge intermittently indicating an empty reading and then return to the correct fuel level indication.
Cause
This condition may result when fuel blends containing aggressive sulphur compounds react with the fuel sender assembly, which may result in voltage spikes being induced on the fuel level signal to the PCM. Use of another fuel blend may reverse this reaction and return the system to normal operation.
Correction
Reprogram the PCM with the new service calibration which is available in the June 2003, Techline® TIS release sent to the dealers on 6/28/03. Use the TIS Version 7 or later data update.

 

That's one of the advantages of living in CA - very low sulpher gasoline. I use Shell almost exclusively and my latest smog test showed very low levels of HCs and NOs.

 

It took me a while to dig this up, but here is the circuit board that came out of my fuel sending unit assembly when it got replaced. You can see the black deteriorated traces... they should be as shiny as a new silver dollar....

 

What is different about the design of this sender than any other GM car?
It appears to be a silver plated Ceramic material.