Fuel gauge woes

[alderan33]

I have a recently purchased 72 c10 and I’m trying to get the fuel gauge working. I have replaced the sending unit and gauge and tested both outside the truck. I have tested the sending unit wire from the tank to fuse box for continuity. I have tested the printed circuit board for signal. All good. The gauge reads 3 o’clock indicating no ground from what I’ve read. There are two gray wires labeled cluster coming out of the fuse block. One has a female end that isn’t connected to anything. The other goes up under the dash. The wire cluster going into the back of the gauges looks good. Any help would be immensely appreciated.

[RustyPile]

Gauge needle sitting at 3 o'clock with no movement does not mean loss of ground.. It means there's open in the tan wire somewhere on it's journey from the gauge to the sending unit.. What does the needle do when you disconnect the tan wire at the sending unit and short it to a known good ground???

FYI, there are numerous threads on this forum and the ELECTRICAL forum discussing this very problem..

Here is one of them:

http://67-72chevytrucks.com/vboard/s...d.php?t=640615

[Ryanz]

Originally Posted by RustyPile

Gauge needle sitting at 3 o'clock with no movement does not mean loss of ground.. It means there's open in the tan wire somewhere on it's journey from the gauge to the sending unit.. What does the needle do when you disconnect the tan wire at the sending unit and short it to a known good ground???

FYI, there are numerous threads on this forum and the ELECTRICAL forum discussing this very problem..

Here is one of them:

http://67-72chevytrucks.com/vboard/s...d.php?t=640615

I'm still having the issue with mine as well. What I've determined now is the sending unit is working (tried 2 different ones), but as I move the float from empty to full, it reads zero to 90 ohms as it should, but the gauge escalates too quickly and goes above full to the 3 O'clock position. I've tested both resistors off my clusters and they both read 90 ohms. I did all the testing in the link above - like most say, my readings are slightly off but mostly close. I'm not sure what the heck is happening and it's driving me nuts!

[1970cstblazer]

Sounds to me that the fuel gauge is the issue if the wiring, connections, and sending unit check out.