Chrysler Repair: 98 Sebring JX inaccurate gas gauge, fuel level sensor, variable resistor

Question
The gas gauge is inaccurate.  Vehicle ran out of gas when gauge read 3/8 tank.  Also, noticed that gauge has sporadic readings... going down from full to 3/4 full within a few miles.  Any suggestions?

Answer
Hi Paul,
The fuel level sensor is part of the fuel pump module inside the tank. I don't have the wiring diagram for the Sebring, but the Cirrus/Stratus vehicle which is contemporary carries the current flow signal from the sensor to the body computer module which puts the data as a digital value on the data bus which is shared all around the car including to the instrument cluster. If you go to the fuel tank you should find a four wire connector: The dark blue wire is the float sensor signal, the black/light green is the ground wire that is grounded at a bolt at the  left rear of the trunk pan. Probably the most easy check would be to measure the resistance on the dark blue wire as compared to ground (any shiney surface of the body nearby) when the tank is full and when the level has been used partially, comparing the reading of the resistance to the reading of the fuel gauge needle. If the two readings are similarly discrepent to the known fuel level (based on how far you have driven the car and the average mpg) then that would prove that the fuel level sensor itself is not working properly inside the tank. Then you would have to remove the fuel pump/sensor module and inspect the float and the connected variable resistor. You might also want to trace the ground wire to its ground point (I think inside the trunk at the rear edge of the pan, slightly left of center) and verify that the bolt is firm and the surface attachment point is clean and shiney). This analysis assumes the Sebring and Cirrus/Stratus systems are identical. Chrysler is pretty consistent in its electrical engineering so that is a reasonable assumption. If the gauge and the resistance values don't track with each other, then the cluster gauge may be bad, or the connection of the resistor wire at the body computer. But I'd start at the float wire at the tank and see whether it's reading parallels the way the needle on the gauge reads or not before looking at the digital part of the system.
Roland