Questions and Answers

Low Fuel??

Q. My wife and I have a 1999 Ford Taurus, 17900 miles, automatic transmission, V6 engine, Antilock Brakes. The fuel gauge, I don't believe, shows the correct amount of gas in the tank. I feel it shows less than what is actually in the tank. We took the car in to the dealer the other day to have them look at it and they ended up replacing the fuel pump. I still don't think that solved the problem. An example is the other day the low fuel light came on which it is supposed to do when there is 1/16 of a tank of gas still left and since it is a 16 gallon tank that means there should be one gallon left in the tank. We go to fill the tank and it only takes 10.606 gallons to fill the tank. Could there be any other problem that the dealer may want to check?

Please respond when convenient.
Thank You!

A. The low fuel light is activated in one of two ways. There is a separate low fuel sensor that can be adjusted or a circuit in the sending unit that activates the light which can not be adjusted.

I don't have a sending unit for that car handy, but I do have a pretty good picture of one. It does seem like the one in your car has a separate low fuel sensor. This can usually be adjusted by sliding the sensor up or down in it's retainer. Keep in mind, also, that this is not a fine adjustment, it is more like a ballpark adjustment.

I usually set it in the mid range where the light will come on at about 2.5 gallons. Your's might be set at the upper range where it will come on at about five gallons. This can be difficult to do in your car because the gas tank has to come out to remove the fuel pump/sending unit assembly. You also have to keep in mind that there is about one gallon of gas in the tank that the pump can't get to. This is done intentionally so that any water or junk will not be picked up by the fuel pump.

So, if we do a little math, you have one gallon that doesn't get used and one gallon for the sensor. That leaves you 14 gallons so you are only off by about three gallons. With a four gallon warning, that gives you about a 60 mile driving range before you run out. That should be enough to get you to a gas station under almost any driving situation.

Personally, I would not want to wait until there is only one gallon of gas left in the tank before the light came on. This might be okay if you never leave town and can fill up as soon as the light comes on, but if you travel on the highways, one gallon may not be enough to get you to a gas station. This is especially true on Interstates where service areas can be up to 50 miles apart.