I replaced my ECM on my '93 coupe recently and now my fuel gauge seems to be a bit off. Before replacement, my reserve lite came on, I switched to distance to empty (DTE) and ran it down to about 20 miles before stopping for fuel. On Saturday (after ECM replacement) my reserve lite came on, I went to DTE and it said 72 miles. Less than four miles later, the DTE was down to 68 miles (sounded remarkably accurate to me) and I promptly ran out of gas.

After spending an hour and a half on the shoulder of I-285 in Atlanta, I got roadside service and was back on the road. If you know Atlanta drivers, you know this is not where you want to be sitting!!! I'm just glad that when the service truck showed up, it was a big heavy truck so if somebody decided to mess up, we would be somewhat protected while fueling the vette.

I'd really like to know if there's a way to recalibrate the gauge so I don't have to worry about stopping for fuel before the reserve comes on. Otherwise, I'll be filling up at the quarter tank line just to be safe. I'm just concerned I'll be on a long drive some day and zone out, missing the quarter tank thing. I'll be tooling along and the reserve lite will pop on just in time to tell me I'm about to be screwed again.

I've got the factory GM service manuals and they don't mention anything in the ECM or sending unit service areas about a recalibration. My replacement ECM was used, so I'm guessing it's still carrying the calibration info from the donor car but don't really know if that's where it's stored.

 

The DTE display is notoriously innacurate. Filling up at 1/4 also prolongs the life of the fuel pump. Why push it to the reserve?

 

I guess the biggest reason to push it is, I drive this one quite a bit over the road. If I have to shorten the range by 70 miles or so per tank just to be cautious, it can add an extra fuel stop on some trips. Many of my trips are in the wee hours of the nite and I'd rather stop as few times as possible. It's not an unthinkable situation, but an accurate gauge would make traveling in this one more convenient.

And then there's the 'zone out' factor when sometimes I just don't notice until the stinkin' reserve pops on. It's one of the hazards of having a vette that is also a great over the road traveler. Oh well, I guess I'll live with it.