D100 Fuel gauge inop - DodgeTalk : Dodge Car Forums, Dodge Truck Forums and Ram Forums
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post #1 of 4 Old 04-23-2019, 09:16 AM Thread Starter
John's Dakota
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D100 Fuel gauge inop

I have a customer truck (1964) that I can't get fuel gauge to work correctly. I replaced voltage stabilizer with electronic one per the thread I saw. New sender that reads correctly 44 ohms at half tank. Reference voltage 5V at sender wire and also temp sensor wire. Ground is good. Short wire to ground and gauge pegs. Connect sender gauge doesn't move. Any idea what I'm doing wrong? Thanks in advance for your help. Also temp gauge pegs when grounded but not when connected to sensor (270 ohms).
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post #2 of 4 Old 04-28-2019, 12:21 PM
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Are you sure the guage is grounded? What is voltage after sender? The resistance in the sending unit will change the voltage going back to the guage. Either the voltage is not getting to the guage (bad sender) or it has nowhere to go after the guage (bad ground).

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post #3 of 4 Old 05-08-2019, 03:31 PM Thread Starter
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Finally. Fuel gauge reads full at fill up. Problem was the gauge. I believe the resistance wire on needle was shorted due to eroded insulation. It had me scratching my head. Thanks for your reply.
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post #4 of 4 Old 05-14-2019, 06:44 PM
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The circuit is just an ammeter ( fuel gauge) and a variable resistance (the sender) in series with the battery. The circuit is completed through chassis ground. When the tank is full the float in the tank moves the sender to minimum resistance and the gauge reads maximum current ( full scale). As the level in the tank drops, the resistance goes up, less current flows and the gauge drops. If you read full on fill up and the gauge drops to empty when you shut the car off, there is nothing wrong with the gauge. Any weird readings with the ignition on are caused by a screwed up sender. A missing gauge ground is an open circuit and the gauge would always read empty

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