Quote:
Originally Posted by Firebirdjones
Been a long time since I had to trouble shoot one,,,but I believe if you ground the sending unit wire,,turn the key on,,,,,it should move your gauge to full. Un-grounding the wire and the gauge should drop to empty.
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Close, just the other way around. Grounding is empty, un-grounding is full
Your gas gauge is just reading a resistance at the sending unit, with zero resistance being empty (zero resistance is basically a direct path to ground), and 90 resistance reading full.
So if you take the sending unit out of the equation, and ground the sending unit wire, the gauge should read empty (with the key "on"), because you're showing it zero ohms.
Un-grounding the wire should show way past full, because it's expecting up to 90 ohms and you're showing it a million ohms.
If you want to get fancy with it, your local radio shack will have an assortment of resistors for about 10 cents each. Pick a couple under 90 ohms and connect them between the sending unit wire and ground. 45 ohms will read as 1/2 a tank, 30 ohms will read as 1/3 tank, ect ect.
Likewise, you can attempt to read the resistance from the sending unit directly with a standard multi-meter.