tommyg

1998 conv gas gage goes to empty after 20 to 30 minutes running at 70
MPH above 85 degrees. Have used Techron. Did not have problem in hot stop and go traffic. This seems to be heat related to expressway
travel. After stopping and shutdown the gage will come back if left to sit for around 30 minutes. When getting back on expressway gage will
go back to reading EMPTY after about 15 minutes. Once gage goes to
EMPTY it will not reset until you shut down and let it cool down. All other engine gages and readouts are normal.

corvettezman

Sounds like your sending unit is shot.
If you have used Techron and that did not fix the problem , then a new sending unit is in order, which of course involves dropping the tank.

DeeGee

The sensors sit submerged in fuel so there shouldn't be anything heat related affecting the sensor. Do you normallty run the tanks low on fuel? If so, switch fuel brands (to try a different additive) and keep the tanks topped up. Clear any codes down and try a few more doses of Techron.

The problem is caused by sulfur deposits on the sender. Techron will clean it up if the deposits are not too bad. If Techron doesn't work some try Sea Foam. If all else fails, then a sender change is needed.

castiman

When I got my 98 several weeks ago my gas gauge would go from full to empty, back to full then to empty and then stay there until I shut the car off for a while. I put a 20 ounce bottle of techron in a full tank ran it down to half a tank then added another 20 ounce bottle. I've put close to 2000 miles since with no problems. I've also have top the tank off when at half full. Besides keeping the sending units in gas it makes my wallet feel better when filling.

Mr.Bill

Maybe the force of the power of expressway driving is keeping the gas pinned on the back wall of the tank away fron the sensors.

I am sure it is your fuel gage sensors.

Jistari

The deposits that form on the gas level sensor cause the float to "hang" and not move, an inherently random situation. So trying to interpret a logical reason why it hangs in some conditions and moves in others is not gonna get you far.

It just hangs

Best bet = several applications of Techron, over time, with good top tier gas, maintain level at 3/4 or above, then sea foam and if after a month or so (several tanks) it doesnt clear up, yup.....may have to look at replacing the sender. Many do report sucess after long periods of erratic behavior if they keep at it with the additives and methods above.

Good luck

Vetteman Jack

Don't know how many treatments of Techron you've used, but give it a couple more tries before going to the expensive repair of replacing the sending units. If that fails, you may have to replace the sending units.

Mr.Bill

Hmm, I will have to think about this one, I was always under the impression that the gas has sulfur in it and it caused a corrosion buildup on the reading points, This is the first I have heard about the sensor getting stuck.
I guess it is possible.
Mr.Bill

Mr.Bill

The real culprit here is corrosion of the traces on fuel level sensor which is part of the fuel sending unit assembly. Unfortunately, these cannot be purchased separately... you have to by the entire fuel sending unit assembly. There are two as there are two tanks.

Check out the corroded traces... the dark colored gunk. These traces should be as shiny as a brand new silver dollar

dgrant3830

I had this same issue for years on my '99. Techron wiould help for a while but it always came back. It was my DD for a minimum of 120 miles a day so I was going through a lot of gas. I came across a firmware update for the calibrations of the tank sensors though and paid to have it put in. No more problems since for me.

Carcass

Try reaching under the car in front of the rear wheels,and unplugging/plugging the connectors to the sending units 2 or 3 times-being on the bottom of the tanks,they're exposed to all kinds of road crap,and they can get corrosion on the connections(even through the "waterproof" connectors)
My gauge hasn't screwed up since I did this on my '98 a year ago.
I do use Techron as a preventative measure,but it wasn't what fixed my gauge-cleaning up the connections was.

DeeGee

This is the reflash that Dave is referring to:

Document ID# 1351974
2002 Chevrolet Corvette
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.

FFIN90

You can buy the sensor kit for the LEFT side only, I have one I just purchased from Gene Culley.

Jistari

I've never held one in my hand Bill (so I didnt know how firmly the nib presses against the contacts there and always thought the deposits were causing it to stick). The bolded text from the flash Dee posted does seem to indicate it may not be a "sticking" thing but more of an "intermittent spike" thing.

But the I guess what I said still holds true in that whatever the cause, the result is irregularly irregular, so when it happens to people and they look for logic relating to why/when it happens....they're not likley to find any.

Wont be the first time I was "right" when I didnt know what I was talking about

red-in-la

I had the gauge peg empty in my 2000. The next morning it was still reading sub zero. I reset the codes in the DIC and, lo and behold, it is working again. Thanks to the forum for the tip!

Stopped at CostCo and got a 6 pack of Chevron Tech for $17 and will start a regimen on it.

Also noted there is a only use once every 1000 miles notice on the back of the bottle. That note is accompanied by "or as needed".

cletus

My '01 gauge went to zero and I lived with it for a couple of tanks; then read here about Techron and even though I was skeptical I decided to give it a shot before taking it to the dealer. 40 miles into a new tank with Techron and I'm back to normal.
Thanks again to the Corvette Forum I saved a ton and know a lot more about my car.
If Corvette Forum was a girl I'd kiss it... Thanks everyone!

Luweegy

I just changed my float assembly with a new one from Gm and it was fine till I hit 70-80mph then it went to empty again?