QuestionThe gas gauge was working fine. One day it said one quarter of a tank but I ran out of gas. When I shut off car it goes to E. When I start up it goes back up to quarter of a tank and stays there no matter how much gas I put in. What could this be?
AnswerI believe the in-tank sender has failed. The only way to investigate this is to drain and drop the tank, and take the sender out and have it tested electrically. It is possible that the float has stuck, or else the internal rheostat has failed in some way.
You can verify this yourself it you want, by getting a known good sender and connecting it to the wire that goes back to the tank sender, grounding the metal holder to the chassis, and then swinging the arm on the float up and down to see if the gauge follows the position (key on, of course). The indicator doesn't respond immediately - it should be very slow to respond, and move in pulsing increments, but it should slowly approach the right indication if you hold the float arm steady for a minute or so. If that seems all OK, you can just swap out the sender and make sure it is well grounded to the tank and that the wire going to is in good shape.
If testing the rest of the system in this way does not produce correct indication at the dash, the dash unit must have failed - but this is so very rare that I would check and double-check your setup before you conclude that!
Dick.
