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Discussion Starter · #1 ·
I am trying to get a truck running that has been sitting in our yard for 10 years. When it was running before I never noticed that the gas gauge is pegged past full. I just noticed that the other day. Ive been doing some research on what the problem might be and people are saying it's an open circuit in the power to the sender. I did find a cut wire coming from the bulkhead that is tan and looks like the same color and gauge as a piece that was plugged onto the sender. I have no idea why it was cut, but I spliced in a new wire, grounded the sender, still pegged past full. I pulled the instrument cluster and didnt see anything wrong, and I don't see any more damaged wires under the dash. I also cleaned the contacts on the back of the gas gauge. I'm not even sure the wire coming off the bulkhead is for the sender but I dont know what else it would be for. I will post a picture tomorrow of the wire.
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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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If it has been sitting for 10 years and has an electronic guage/sending unit, it could be corroded internally, thereby breaking the circuit internally.
 

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Discussion Starter · #3 ·
If it has been sitting for 10 years and has an electronic guage/sending unit, it could be corroded internally, thereby breaking the circuit internally.
we already dropped the tank and checked the sending unit. It looks fine, doesnt really look corroded. We put a new tank and sending unit in it about 10 years ago but we couldnt register the truck so we never drove it.
 

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Discussion Starter · #4 ·
this brown wire was cut. I plugged a wire onto it and ran it to the sender. Is this the correct wire for the fuel gauge? I dont know what else it would be for and it is the same color as another wire that was plugged onto the sender that was also cut. I think it may have touched the exhaust and melted and the previous owner cut it off.
20210604_094535.jpg
 

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For an electromagnetic gauge to peg, it requires current, no current the gauge should read below empty.

Does the needle move when the key is off?
 

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Discussion Starter · #6 ·
For an electromagnetic gauge to peg, it requires current, no current the gauge should read below empty.

Does the needle move when the key is off?
The gauge reads about 1/4 with the key off. The gauge is getting current through the dash but no resistance through the sender. When you turn the key on it immediately pegs to 3 o'clock.
 

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Exactly. The tank sending unit is shorted out.
Try an ohm meter and see if moving the float up and down changes the resistance.
 
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