Strange Fuel Gauge Reading

Yesterday, my fuel gauge showed between 1/2-1/4 tank when the low fuel light went on. Anyone know how this system works?

alan

There are two separate sensors in the tank. One is for fuel level and the other is for low fuel.

If your tank truly was 1/4 to 1/2 full then the low fuel sensor may be faulty...or the wiring to it.

Well, what I discovered by doing a little web search is that the fuel sender on the 84 is both the gauge and the low fuel light. This morning when I went out to the car, the gauge was now reading "E" with a low fuel warning light. I am thinking defective fuel level sensor. I also found a diagnostic where by you use various resistors to check the fuel gauge at various electrical resistances so I guess that is the first step.

thanks Peter.

alan

Check all the wiring, from the top of the tank to the fuel gauge itself. Porbably you will find some wire broken or some corroded conector.
The fuel gauge, as the temnperature gauge, are secured to the instrument cluster mother board by a stud and nut that works as ground conection as well. If the nut is loose, the electrical conection may be poor and give wrong information.

Good luck!

I am starting to forget what year our various cars are from. You are correct; the dual sensors are from 87/88 and later; I believe.
Signor Pinto is right on the money; sounds like a poor signal/ground...the simplest explanation is usually the most accurate

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Archeo-peteriX
I am starting to forget what year our various cars are from. You are correct; the dual sensors are from 87/88 and later; I believe.
Signor Pinto is right on the money; sounds like a poor signal/ground...the simplest explanation is usually the most accurate

Senhor Pinto is my father, he sends his best regards!


Only Alan will tell, on old cars like ours it is wise to check basic things first, specially problems related to ageing, before going out replacing expensive old stuff.

I will check it but here in Southern California, we almost never have electrical issues. When ever I pull stuff apart, the electrical connectors are factory fresh. But I will pull the rear seat and dash module and see what's doing.

After 26 years, I would be leaning towards a part simply wearing out.

alan

Isn't there a condition where the fuel gauge reads funny along with the temp gauge when the si batteries are going south? I seem to be having both issues on my 88 325is.

Rick

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rkj
Isn't there a condition where the fuel gauge reads funny along with the temp gauge when the si batteries are going south? I seem to be having both issues on my 88 325is.

Rick

Yes Rick, but not becessarily related to the SI board. The main board of the instrument cluster may have bad conections or cracked solders, causing all sort of trouble.
My car had a bad SI board and still gave all good readings, including the fuel consumption below the tacho.