The fuel gauge in my Biscayne always reads between 1/4 and empty. I ***umed it was the ground since the previous owner put in a brand new tank and sending unit alittle over a year ago. I undid the ground, took a wire wheel to the frame where it was mounted to and cleaned it, then bolted it back up and nothing. I had my wife come out and set in the car with the key on while I jiggled the wires. I jiggled and completely unhooked the ground and she said nothing happened. I then jiggled the wire that goes from the sending unit to the gauge and she said it fluctuated alot (From Empty to Full and everywhere and in between). Do you guys think its just the connector on the wire where it goes to the sending unit or do you think I should replace the wire? Only concern I have is why did it fluctuate from Empty to Full when I know the tank isnt full.
I could be wrong but, either that wire has a bare spot on it or something is shorting out in the top of the sending unit
The previous owner may have put in the wrong sending unit. The gauge and unit must match in resistance reading. You can't use a sending unit that reads from 0-30 Ohms with a gauge that's looking for a 0-90 OHMs.
60 biscayne gauge is 0-30 ohms. The gauge might be bad, the sender might be bad, the wiring might be bad. I would start by testing the gauge, go to radio shack (or a real electronics store) and get some resistors, 33 ohm and 10 ohm. Disconnect the sender wire from the sender, at either end. Connect the sender terminal on the gauge to one end of the 10 ohm resistor, and connect the other end of the resistor to ground. The gauge should read 1/3 full. Repeat this with the 33 ohm, it should read full, but not "pegged" past full. Another approach is to use an ohm meter to test the sender. Disconnect the sender wire from the gauge, and measure the resistance of the sender wire to ground. If the tank is empty, it should read 0 ohms. If it is full, it should read 30 ohms. If it is half full, it should read 15 ohms, etc. If something is shorted, it will read 0 or close to it. You can keep isolating the problem by measuring the resistance at the sender itself. You can also take the sender out of the tank, and see what the resistance is, as you move it thru it's travel from empty to full. sometimes the sender will have a mechanical problem, like the float has a leak and stays at the bottom of the tank, or maybe it hits something in the tank for some reason, and can't travel up like it should. Or the wire wound resistor in the sender might be messed up somehow, or the contact, or something like that. Hopefully this will get you started. Ask more questions if you don't understand.
I had a brand new gauge and sending unit that was erratic and after checking everything I found that a rivet on the sending was a bit loose, had caused slight arcing between the surfaces and corroded enough to prevent a good contact. I had to remove the rivet, clean the metal and re-rivet to get a good contact
When there is a loose connection on the sender, the gauge will peg "full" when it loses contact. This problem is the opposite. But thanks for pointing out that it's quite likely that the new sending unit doesn't work right.
Thanks for all the input guys! Squirrel...I'll keep you in mind. When all this crazy weather we are having straightens up I'll try what you said and if I have any questions I'll message you
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