so my fuel gauge works but it stays full until about 100 miles, goes slowly down to 3/4by 200 and 1/2 by 250, by 270 its below 1/4 and then its accurate the rest of the way down. on my search to see if this was fixable, one post said it may be the fuel level sensor. any help with this would be much appreciated.
Fuel gauges are never really accurate.
Once you get to know your car enough you'll be able to tell with the mileage you've driven how much actual fuel you'll have in the car if it's maintained properly.
Also the fuel gauge sending unit only tells you what it sees and the manufacturer can't make or devise a way to have it accurate to a tee.
This again is why you'll need to pay attention to your mileage vs gauge to get an approximation of how much farther you can drive the car if you know what you're gas mileage is and if it's consistent.
The other thing you could do is replace the sending unit or actual pump that the sending unit is attached to and you'll probably still have the same effect with the gauge in your dash.
Anyway, I hope I've explained it enough for you to get an understanding of what to do and good luck with it.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO! 
yea thanks that's what i do now, keeping up with the mileage, i was just wondering if i could do anything about it.
Well besides replacing the fuel pump or the actual fuel level sending unit in the pump assembly that's about it.
If you chose to go this route, I've got an excellent write up on changing out your fuel pump which anyone can do if they follow the directions.
Simple tools will be all you need and some time and you can change it all our by yourself if you have to.
Good luck with it and fill it up more often than usual.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
it wouldnt matter ive owned 4 cavaliers all have done the same thing, 60-100(freeway, city) miles when you fill it up before it really even moves..
head over to your local Walmart and pick up a bottle of Techron Plus. It's 5$ and it's supposed to help your fuel gage. It's the same stuff GM sells at the dealership (TSB for this problem). It's worth a try if it helps then you solved it , if not then you need to get a new gauge. Mine is broken, I just refill it every 350km. I plan to replace the gauge if my fuel pump dies.
