Question about 1991 Buick Regal

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Fuel Gauge Issue

Fuel gauge never goes below the F regardless of actual fuel level, when it is allowed to sit overnight the needle will lower itself to the right hand side of the full line, but then it is started it steadily turns clockwise another half inch. I was able to remove the clear plastic cover to turn the dial by hand so; when I turn the gauge down to empty by hand, then turn the key to "on" it steadily rises back to past full. it almost sounds like the level sensor is shorted out causing too much resistance in the circuit. looking for second opinion, or even some pointers on how to test the gauge (since I really don't want to drop the tank).

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  • clnielsen Feb 12, 2009

    Thank you for your speedy and experience based response! Is there any way to calibrate these sending units? I'm looking to repair if possible, as opposed to replace.

  • clnielsen Feb 12, 2009

    Well, it was the sending unit, I hooked up a meter and got 0Ω no matter what. it's a problem with the variable resistor making contact with the second contact.

  • clnielsen Feb 12, 2009

    yeah, I got it apart, cleaned it, and found that the little board was indeed shot... luckily, I have some wire identical to the stuff used on the board, and am currently re-wrapping the board with new wire (this is a real pain in the ****, never try it :p)


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I know you don't want to drop the tank and I could lie to you, but the truth is that you have to drop the tank to check and fix this problem. It really is not as hard as you may think. Even easier if you are low on gas. Putting a full tank back up is a real challenge!
So, after you pull the tank down and remove the sending unit/fuel pump, get a ohm meter and set it to Ohms. Insert the leads one into each opening on the connector on the sending unit plug. Slowly raise and lower the arm with the fuel float on it and see if your ohms fluctuate. Also notice if there is any resistance on the arm as you move it up and down. This is how you check your problem. I have seen it many times before. A new sending unit will fix this problem, though if your ohms are fluctuating and your float arm is stiff, you can temporarliy fix it with a few squirts of WD40. It will start to hang up again after a while though.
Please remember to rate this fix.

Posted on Feb 12, 2009

  • Tommy Walker Feb 12, 2009

    No, not officially. However if you can pull the contact out coming from the float arm so that it makes contact with the actual sending unit board you might get it to work. Also, take a pencil eraser and clean the contacts on the arm and the sending unit board. This is assuming that your electrical board is not completely shot. Inspect all of the wires also and clean any corrosion off and be sure the ground is tight. I have fixed them but with varying results. Otherwise a new sending unit will be needed. I looked the part up for you at Auto Zone and they sell the sending unit for $146.99. This should give yu a general guidline as far as price. I hope all of this helps. Good luck.

  • Tommy Walker Feb 13, 2009

    I know, that is why I quit doing mechanics work! Imagine trying to make a living with it, answering questions is much more laid back! Anyway, you will get it. Take your time and check the sending unit before you put it all back together. If the electrical is working then you have fixed it. Be sure to use an emery cloth or fine sandpaper and remove all of the rust from the float arm and any other metal parts before dropping it back in the tank. Spray WD40 on all of the mechanical parts and as an extra precaution after you spray with the WD40, liberally coat all of the same parts with White Lithium Grease. Be sure not to spray any of the electrical components and recheck it AGAIN before you put it back in the tank. It has been a pleasure helping you and please let me know the outcome.


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