Fuel Gauge Issue

[DJ53]

Fuel gauge shows just under half when empty. Removed ground .. goes to Full. Removed gauge checked power on gauge clips .. 12v and showing about 11 ohms on signal line when about half full. Disconnected sender from wiring harness on frame rail in front of tank ... normal pink and brown wire and waterproof connector ... found 5 volts on power line (pink I think) instead of expected 12v .. Any idea what is happening? Also... the gauge was working normally and after filling i saw the gauge steadily decline to its new home just below half. Don't normally see them at the moment they fail!
I also connected 12v to the gauge on my bench and applied various resistors to the signal post including a dead short ... gauge worked as expected.
Shouldn't I have 12v on the sender connector?
Sure hope its not the sender ..... .

Thanks for any help!

 

[Charlie]

 

[C10MixMaster]

Fuel gauge shows just under half when empty. Removed ground .. goes to Full. Removed gauge checked power on gauge clips .. 12v and showing about 11 ohms on signal line when about half full. Disconnected sender from wiring harness on frame rail in front of tank ... normal pink and brown wire and waterproof connector ... found 5 volts on power line (pink I think) instead of expected 12v .. Any idea what is happening? Also... the gauge was working normally and after filling i saw the gauge steadily decline to its new home just below half. Don't normally see them at the moment they fail!
I also connected 12v to the gauge on my bench and applied various resistors to the signal post including a dead short ... gauge worked as expected.
Shouldn't I have 12v on the sender connector?
Sure hope its not the sender ..... .

Thanks for any help!

I can't say for sure on the 5 volts but i think that's probably rite. If you ground it and it goes to empty and open it goes past full the gauge is good. 1/2 tank should read 44 ohms. sounds like a sending unit.

For Truck Years: 1967 - 1990
The Fuel Gauge Needle Should Point to:
Left Line (Empty) when sender resistance = ~1 Ω
Middle Line (Half) when sender resistance = 44 Ω
Right Line (Full) when sender resistance = 88 Ω

 

[DJ53]

Thanks for the feedback .. I found and old working sender yesterday... I plan to connect at the wiring harness plug where the current sensor is .. and see what happens .. it has the same 0-90 range.