TAC Tech => Electrical => Topic started by: Avalanche on April 10, 2021, 12:28:37 PM
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Anyone got a schematic for the wiring from the fuel tank/sender forward? My gauge is not working.
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Not much to it. One wire from the sender to the gauge. Then the gauge gets power from a pink wire. You can test for power at the pink wire. If it has it, try grounding the other terminal and see if the gauge reacts.
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Is the gauge pegged right off the face to the right? If there is a good grounding it will pull back onto the dial. Check the ground wire under the rear panel, clean the metal and refit, easy thing to check.
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Hi all - it's stuck in the middle. I disconnect the wire near the tank and the gauge goes past full, which from I read is right - I just have to ground it now to insure it goes to empty. If that happens it seems I have an issue with the sending unit. Right?
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Avalanche,
You are correct. Second generation Firebirds have 90 ohm sending units. 90 ohms should read a full tank and 0 ohms = empty.
As Wallington mentioned, there is a ground wire from the sending unit on top of the tank that runs to rear panel area right behind the tank. Not far from where the filler tube is located. If the ground is broken, dirty or corroded it could cause a high reading on the gage.
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That seems to indicate it is grounded and gauge working, how accurately is hard to say. If you don't know the history of the sender unit then it is probably overdue for dropping the tank anyway, new fuel hoses, pickup sock, maybe a buildsheet.
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You can guess where this is going: Zero ohms is empty. The gauge has to be accurate at "E" and that's how they did it. If you can't get the gauge to show E then it's the gauge. If the gauge does show E with that wire grounded, then evidently you don't have zero ohms in the tank, for whatever reasons that could be.
The gauges do go bad somehow.
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It's sounds to me that your float is clogged and stuck. The gauge and wiring is fine if you disconnected the ground and the gauge dropped.