I just took a trip to new york . I live about 2 hours away . I had half a tank according to the auge or maybe a little less than that . when i went to put gas in PA it took 13 gallons, the I drove to new york and came back and I still have 3/4'* left ! Is there a problem or is there a problem ?
My custom intake fell off so I gutted out the factory one with a K&N and I also have a Dynomax muffler . I use 93 octane and ALWAYS add the fuel injector cleaner. About 1000 miles on the plugs and wires , stock tire size and they were properly inflated.
If there is an electrical problem , does anyone want to buy a bonneville with a screwed up gauge ???
I just don't have time to fix this .

you have an SE and you're using 93 octane? why? do you notice pinging or power loss on 87 or does the manual for your year recommend premium?

I thnk I remember seeing a TSB about this problem.

I know that my gas gauge moves very slowly towards 1/2 tank, then drops really fast after that. I think it is one of the quirks of the 92-99 Bonneville.

Yup, i got the same prob. Two nights ago i was driving around and my gauge went from half to empty and back to half again in about 15 min. really wierd. i just know that as soon as it goes under half to fill it back up again.

There was a TSB. Wasn't it something about adding a resistor?

I don't think there is an easy fix without major surgery at the fuel tank. My fuel gage basically failed on full several months ago. I noticed too that it wasn't always a linear tracking as the level went from full towards empty. Many years ago I started using the trip meter to gage fuel level/consumption anyway so it'* not a big deal that my fuel gage is faulty. When I reach approx. 325 miles on the trip meter (with my driving habits) it will usually take 15 to 16 gallons every time.

What'* the procedure to remove the tank?
I would hate adding a resister , I like to do things the right way or no way !

We need to find that TSB. I think it had something to do with adding a resistor bridge across 2 contacts on the fuel level sender connector at the top of the tank. My own gauge does this to some extent, the top half of the tank lasts longer than the last half, but no different than any other GM car or truck I've owned. The volumes are different between the 2 halves, anyway. I'll poke around and see if I can find it.

Doesn't DeathRat have all of those?

I still have the copies of all the deathrat files....but they're at home. I'll go through it all and see when I get off work.