1999 Buick bad fuel gauge

I inherited a 1999 Buick Park Avenue from my mother (120,000 miles). For a while the fuel gauge acted properly, but then suddenly it began to be erratic at about 1/4 of a tank – sometimes dropping to zero, sometimes going tp “full” and then back to zero (or back to “full”). One mechanic suggested that my mother had never let the tank drop below 1/4 before gassing up, and that as a result the fuel sensor had become erratic at that level. The only way to know how much gas I now have in the tank is to (1) fill it up completely, (2) keep track of the fuel consumed (there is a read-out on this car for that). That certainly is not very accurate or comforting.

I want to fix it, and the options that I see as possibilities are the following:

  1. Drop the tank, replace the sensor (expensive)
  2. See if a fuel additive will “unclog” things and allow the sensor to work again (any suggestions?)
  3. Drive it BELOW 1/4 of a tank on purpose, keeping a gas can in the trunk for when I run out. Keep doing this until the fuel sensor works again

As an aside to “option3” I understand that the fuel pump in some cars will NOT PUMP again when air is introduced (they won’t “self prime”). Is that the situation with this make, year, and model? In other words, is option 3 just inviting MORE trouble?

Are there other options? Any help or advice or opinions are welcomed.

Many thanks!

If you want the fuel gauge to read correctly the fuel pump assembly requires replacement. http://www.rockauto.com/catalog/moreinfo.php?pk=4550919&cc=1352810

Is you can see, the thing’s made out of plastic. And the plastic arm for the float is where these pumps usually fail for this problem.


Thanks for your comment and your help.

Also, don’t deliberately run out of gas. Not only can’t you predict where you will run out (inside a tunnel, on a drawbridge or train track), but running the pump dry is a good way to burn it out! (it’s cooled by the fuel, you see, and running it in an empty or nearly empty tank could well doom the fuel pump.)

This is a common problem for GM vehicles of this vintage. Sulfur in the gasoline corrodes the contacts on the sensor. Chevrolet sells a fuel tank additive to clean the sensor, but I’m pretty sure it’s repackaged Chevron Techron. I would try a bottle or two of Chevron Techron first to clean the sensor.

Don’t run the car to empty, it is not good for the fuel pump or your safety.

The gas gauge failed on my 2000 Blazer about 3 years before I traded it in. To fix the gauge I would have had to replace the entire fuel pump assembly. Since I tracked the mpg on the truck I was able to come up with a max distance to drive with a ~3 gallon reserve. It worked out to 240/255 miles (winter/summer). As long as I filled the tank each time I never had any issues. I ran out of gas one time because I forgot I didn’t fill the tank completely. There’s very little warning, the Blazer sputtered once and died about a mile afterwards.

I suggest you calculate the mpg over a few tanks of gas and pick a max distance that will leave a healthy reserve (~3 gallons), note winter mpg will be a little lower.

Ed B.

You can try the Techron, but chances are the tank will need to be dropped to fix this. I replaced the assembly on my Ford recently due to a failed pump, then had to drop the tank again when the fuel gauge failed. The sender popped off the assembly and was just dangling. Good old cheap plastic clips.