QuestionRoland I read this question and answer you gave someone as I have the same problem and would like to add the resistor. Please advise how I woul do this. Below are the question and answer what I read. Thank you.
Question------
I have a 2000 Cirrus LXi, and when the gas guage gets to 1/4 of a tank, the engine will start to sputter. This has happened 3 times within the past month. It will eventually die, after limping along for about 1 mile. The low fuel light never comes on, but it seems to be out of gas. When gas is put into the tank, the vehicle will start again, but not until you rapidly pump the accelerator. I was told that it might be the sending unit in the gas tank, but was wanting another opinion. If it is the sending unit, about how much $$$ are we talking about fix the problem? I would like to keep the vehicle for at least another 2 years, considering it is paid off. But if it is going to cost too much, then I would like to try and either sell it or trade it in, but note the problem to whoever gets the vehicle.
Answer-------
Hi James,
I suspect the fuel level sender unit that is operated by a float on an arm that is attached to a variable resistor is inaccurate, but the fact that it is off by about 1/4 tank band still reading smoothly from full to 1/4 means that it is reliable except in the absolute sense. The tank holds 16 gallons so I would wonder how much gas it takes to fill your tank completely after this stalling has happened? If you find that it takes 15 or more gallons then that means you have had this problem because of too low a gas level in the tank, rather than a failure of the fuel pump's abilities when the level is low. You could go so far as to change the sender unit but that means dropping the fuel tank from the car and would not really be economically justified. I don't know how much time and cost is involved but not only that but disturbing all the other parts just opens a can or worms unnecessarily from my point of view. I would consider doing that job only if the fuel pump were shown to be weak or failed.
The other two choices are to just adjust your view of the fuel gauge to reflect the inaccuracy by filling it at 3/8 reading. Or you could put a simple electrical resistor in the wire from the sender that goes to the body computer which would adjust for the error and shift the reading down scale. Either of those would be how I deal with it. This is not a reason for giving up on the car, it is too minor. Let me know if you want to adjust the reading by inserting a resistor into the line to improve the accuracy. It would be a matter of accessing the wire and splicing in a resistor.
Roland
AnswerHi Nathan,
First I would try a cluster self-test/calibration. Hold in the trip reset button, then turn the key to the 'run' position and whatch for a series of tests to be run automatically. The cluster gauges are cycled through 4 steps in synchrony. The fuel gauge will first show full, then 1/2, the 1/2 again, and finally E. That might improve the accuracy of the gauge.
If it doesn't, then you could try the resistor modification approach. I am not certain what size resistor to try but it probably is in the range of 25 ohms, and I am not certain that it will shift the reading downscale but give it a try.
The resistor is easiest to insert in the circuit if you go to the rear of the vehicle where just below the trunk latch, slightly to the left of it, you will find 4 black wires held by a screw to the metal (there might be 2 wires held by one screw and 2 by a separate screw as an alternative. Note that two wires will be thinner, and 2 wires will be fatter. The two fatter wires are the ones to deal with. Detach one of the two fat wires and notice whether the fuel gauge reads differently compared to before doing that, If so that is the wire to use. If instead the gauge reads the same then the other wire should be detached and to see if that modifies the gauge reading. Once you know which wire affects the reading, try attaching one end of the 25 ohm resistor to the end of the wire, and then attach the other end of the resistor to the grounding screw. Then see if tha gauge has shifted in the direction you want it to move or not, and by the amount you believe it is inaccurate by. If it moves in the wrong direction then this idea will not work. If it moves in the right direction but not the correct amount then change the size of the resistor until it does.
Roland
