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I still see questions/comment concerning the well known fuel gauge problem, along with fixes, such as change gas, use Techron, etc. Usually, turning the car off and on again clears the problem. Anyway, after a bit of Googling, I found the "official" GM notice:

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Erratic Fuel Gauge Reading (Reprogram the PCM) #02-06-04-010A - (Jun 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.

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My C5 was done probably not long after this came out - I was having another problem fixed and the dealer said there was a PCM update - this was it. I had the gas gauge problem all the time before the fix - never since.

 

VERY GOOD INFO !!!!! Thank You Sir !!!!!!!!!

 

Any idea what constitutes a " fuel blend containing aggressive sulphur compounds react with the fuel sender assembly" ? Is this geographical, non tier 1 fuels like at the grocery mart vs Shell?

 

I was told that gas from South America has a higher level of sulphur. I don't know how true this is, at one time I was using Sunoco and had problems since switching to Shell none at all. That was 12 years ago.

 

All I can say is after 6 months of trying Techron, etc.. and having the right sender code I got a new right sender from Amazon, swapped it out no issues since. Much happier driving with no warnings and gauge on E!

 

Short story: the contacts in the fuel senders contain silver. Sulphur in the fuel erodes the silver, eventually causing the senders to read wonky, if at all. Especially problematic in the 2001 model year (across multiple vehicles).
For the C5, one solution was to replace the 2001 senders with 2002 senders, (which were apparently identical except silver solder was not used) - but GM would not authorize warranty replacement of a 2001 part with a 2002 part.

Anyway:
Different manufacturers and differerent geographic areas all have different sulphur levels.

RFG III (CA emissions) is mandatory in CA and several other high density areas of the country, and voluntary in other areas.

RFG III is generally the lowest sulphur content, but within that, there is still a huge variance.

When I had the same problem, I contacted most of the fuel companies that provide for this area (SE VA). Told them the problem, and GMs recommendation to switch to the lowest sulphur fuel available. In the process, I also learned SE VA to DC is a voluntary RFG III zone.

At the time (about 12 years ago) sulphur content for the major players (Amoco/BP, Sunoco, Shell, Texaco, Mobil) varied from 90ppm to 230ppm.

At the time, Amoco had the lowest sulphur content for RFG III (which I was already using).

For areas of the country not using RFG III, sulphur content is higher.

Also learned no-name gas is generally delivery overrun/excess from the majors, resold at discount at the local distribution point to places like Walmart, Costco, et al. What's in their storage tank may be a mixture from multiple manufacturers.

 

Costco is top tier gas. The other discounters? Who knows. The local wholesalers have bulk gasoline, to which they than add the various "brand name" additive packages, to "make" Exxon, Shell, etc., etc. And there are still places where you can get "pure" (no additive package) gas - not a good idea, IMO.

I run either Costco or my local grocery store own brand - both are cheap, both work, neither cause problems in any of our vehicles. Before I had the reflash, I ran only top brand name gas - still had gas gauge problems.

Anyway if you are going to get a custom tune, at least get your PCM up to date beforehand.

 

Thanks for all this useful info. Never has a fuel gauge issue and hope that trend continues. I do add a bottle of Techron Concentrate about twice a year.

 

I use Shell nitro exclusively so hopefully that helps. Ran Sea Foam through once as the car has sat for a while before I got it. A bottle of Techron may be a good idea but supposedly Shell Nitro has that in it. No issues. Can't find data on sulphur content but will look later. Great information above Gents...