Chrysler Repair: Fuel guage sending unit, gas gauge, jeep products

Question
My gas gauge stops at about 1/4 and never goes to empty and the low fuel light does not come on when almost empty. Fuel light does function at startup. I got to tank in trunk but do not know how to remove sending unit from the tank to check.Can yoy tell me how to remove sending unit to inspect. Jeff

Answer
I'll need to know what kind of chrysler you have before I can give you more information on the removal process.

Across the board though sending units have been problematic for chrysler and jeep products.  Checking them with a multi-meter can SOMETIMES show you proof positive what's wrong but other times you just have to replace it and move on.

Let me see if I can do this right.


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Basically what you see above on the left is a group of circuits.  They are all tied in at the left and as they go to the right the resistance gets higher.  The section on the right that's kind of hanging down is and indication as to where the fuel float is.  The float contacts a shorter circuit at the top so it's resistance value is less.  As the float moves downward the bars get longer and so the resistance increases.  This change in resistance is interpreted by the computer and based on that information your gauge on your dash moves accoring to the float in the tank.

What happens most of the time, aside from the sending units being junk, is that say you only run your car from 1/4 to 3/4 of a tank all the time.  You never fill up and you never let it run below 1/4.  What happens is you use up the middle of the range and eventually wear it out.  This gives you dead spots and inaccurate readings.

Once you have the sending unit out there will be two wires for it.  They are normally the same color.  Green, blue, and tan are pretty popular.  You'll take a multimeter in the ohmmeter setting and touch one lead to each wire for the sending unit.  Move the float slowly and watch the resistance.  IF you find an open/out of limits section then there's your bad spot.  Replace the whole unit as there is no repairing it.
Doug