[marc_nelson]

I recently purchased a "new to me" boat and was happy to see that it had a full tank of gas during the test drive. a couple of days later i stopped by the gas station before my first fishing trip just to top it off and make sure it was full. it took 11 gallons to top it off, so now i'm wondering why the fuel gauge isnt working. i disconnected the pink wire from the gauge and it went back to empty. then i jumpered the pink side to ground and the gauge went back to full. so that should mean that the gauge is working, right? next i changed out the connections to the sending unit, thinking i may have a bad ground, that did nothing. last night i bought a new sending unit and installed that. when i hooked up the new sending unit it still read full while the float arm was all the way down. i know this isnt a complicated instrument. what am i missing?

 

[Brett]

Check your wiring for corrosion or a loose connection.
Verify that the correct wires are to the correct connection.
Verify solid ground at the gauge. Try another gauge.

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[marc_nelson]

Thanks Brett! i'm wondering if i should take the ground from the sending unit off the gauge and run it straight to the battery?

 

[Brett]

Both the gauge and sending unit need to be grounded.
The sending unit is a variable resistor and the gauge is a current meter.
I believe there should be one more wire to the gauge.
That should be power for the instrument light for night viewing.