Fuel gauge doesn't work on my 71 c10 truck

[Cronicdoc13]

So my fuel gauge was stuck on full,, changed put the sending unit and still doesn't work,, still stuck on full..
I have very dim power on my power tester when I touch the tan wire coming from the sensing unit to the fuse box under my dash,, so I test the open plugs next to that tan wire and the light on the tester lights bright... Anybody know what my problem might be.?
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[TBONE1964]

Originally Posted by Cronicdoc13

So my fuel gauge was stuck on full,, changed put the sending unit and still doesn't work,, still stuck on full..
I have very dim power on my power tester when I touch the tan wire coming from the sensing unit to the fuse box under my dash,, so I test the open plugs next to that tan wire and the light on the tester lights bright... Anybody know what my problem might be.?
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If the gauge is not moving at all, check the fuses and check for power at the number 3 terminal on the gauge cluster connector. This is a pink wire that supplies battery voltage to the fuel gauge and temp gauge.

How does your temp gauge work? If it does not work or does not move away from the cold position, you probably have a problem with power to the #3 (pink wire).

If you do have power at the connector, take a good look at the circuit board on the back of the cluster and make sure it is not burnt anywhere. If this checks, see what happens if you pull the tan wire out of the fuse panel. The fuel gauge should go past full to the 3 o-clock position.

Try these test and let me know what happens.

A fuel gauge that looses battery voltage will stay in its last position it had with power until the problem is repaired.

Take care,
Tom

[CR72LB]

I have the 'same' issue on my 72 C10. The fuel gauge worked just fine until last week when I disconnected the battery for a week while I replaced the timing chain cover gasket and oil pan gasket. Finished that job and the fuel gauge simply stays at empty.

I tried your trick of disconnecting the tan wire from the fuse panel and the gauge went to 3 o'clock. I connected the tan wire again it the gauge went back to Empty.

Any suggestions to resolve the issue?

[cdowns]

did you check the whole length of the wire going to the sender including where it is tucked inside of the floor channel by the door

[In The Ten Ring]

Is your truck out of gas?

LOL. Sorry, that's something my dad would have said.

[Cronicdoc13]

Originally Posted by In The Ten Ring

Is your truck out of gas?

LOL. Sorry, that's something my dad would have said.

Lol...not anymore...that's how I found out the gauge was stuck,, cause I ran out of gas...
But I changed the sending unit thinking that could be the problem but so far,, that's not it..I've checked the tan wire by running another wire from the fuse box where the tan one is plugged, to the little post on the sending unit ,, and nothing changes asfar as my gauge goes..
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[Cronicdoc13]

Originally Posted by cdowns

did you check the whole length of the wire going to the sender including where it is tucked inside of the floor channel by the door

I haven't pulled the whole wire out but I ran a wire in place of the tan wire and no change...
This might sound stupid but,, do you think I need to fill tank up to full to get the sending unit up to where the gauge is stuck at in order to send the signal back to the gauge when it starts to come down.? There power going to the back of the gauge in the dash, but I haven't tested the pink wire in the wiring harness as was recommended here ,, so that's what I'll be trying next,,
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[Cronicdoc13]

Originally Posted by CR72LB

I have the 'same' issue on my 72 C10. The fuel gauge worked just fine until last week when I disconnected the battery for a week while I replaced the timing chain cover gasket and oil pan gasket. Finished that job and the fuel gauge simply stays at empty.

I tried your trick of disconnecting the tan wire from the fuse panel and the gauge went to 3 o'clock. I connected the tan wire again it the gauge went back to Empty.

Any suggestions to resolve the issue?

That's sounds more like a sending unit issue but keep in mind,, I'm also trying to figure out why my gauge is stuck at full and won't move regardless of what I've disconnected ,,
Lol..
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[Cronicdoc13]

Originally Posted by Cronicdoc13

So my fuel gauge was stuck on full,, changed put the sending unit and still doesn't work,, still stuck on full..
I have very dim power on my power tester when I touch the tan wire coming from the sensing unit to the fuse box under my dash,, so I test the open plugs next to that tan wire and the light on the tester lights bright... Anybody know what my problem might be.?
Posted via Mobile Device

I finally got around to ordering a new gauge for my truck,, it's the only thing I haven't changed and that's exactly what was wrong,, my old 71 gas gauge gave up ,, bought a new one for 40 bucks and replaced it and gas gauge works like a charm.! Thanks for all the help everyone here provided.!
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[In The Ten Ring]

Glad you got it fixed. I may be facing the same problem in about 30 days.

[Cronicdoc13]

Originally Posted by In The Ten Ring

Glad you got it fixed. I may be facing the same problem in about 30 days.

Well,, sending unit was 50 bucks brand new,, easy exchange since I still have my gas tank in the cab,, so after replacing that, I went for the tan wire that goes from sending unit to fuse box, and that wasn't it either,, so the last thing was to change my entire gauge, found a brand newby for 40 bucks and replaced it,, and turns out that was the whole deal ...
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[CR72LB]

My gauge is working sometimes. It starting working last night and worked fine until I got in and pushed the clutch, then it dropped all the way to empty. I didn't even have to turn the key and it dropped. Now, it will not work for a few days, then it will work again. I believe it's a grounding issue, but I cannot find any bare wires or anything else that is the smoking gun for my issue. Until I find it, I REALLY watch the miles.