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My fuel gauge does not work, I have checked the grounds, I am pretty sure it is the sending unit. I hooked up a new one outside of the tank that I checked with an OHM meter and it goes from 0 at empty and 30 at full. Now the gauge registers but does not go all the way to empty, it will go to full when I move the new unit all the up but when I move it all the way down it only goes down between 1/4 and empty. any help with this issue would be much appreciated . Thanks mike

It is in a 1954 pickup. Gauges are all new from LMC truck

Try these links.
Fuel Gauge Testing The Filling Station
Gas Gauge Problems fifth ave internet garage.com

Connect +6V to the gauge power terminal. Connect the battery negative or ground lead to the gauge mounting plate. At this point, the gauge needle should go to "full" or beyond. Now connect the gauge sender terminal to ground (or the mounting plate). The needle should go to "empty" or beyond.
The above test will show whether the dash unit is working or not. For an accuracy check, you will need a calibrated variable resistor or a tank unit

Picture Schematic wiring diagram for the fuel level gauge.

I did all those tests, I think I have it working now except it does not go all the way to empty when grounding the sender wire. but with the new sending unit it does go up and down, I did test it first and it read 0 ohms at empty and 30 ohms at the full mark. The gauge just wont read all the way to empty. Even when I tried the new unit outside of the tank. it read over full when the float was all the up and around 1/4 tank when the float was all the way down. Is it just an inaccurate gauge due to cheaply made replacement gauges? Let me know thanks Mike

If you did the below;

Connect +6V to the fuel gauge power terminal.
Then Connect the gauge sender terminal to ground (or the mounting plate).
The needle should go to "empty" or beyond.

And the needle does not go to "empty" or beyond. I would say there is something wrong with the fuel gauge.
I would call LMC and tell them what it is doing.

Mike
I just went through all the testing procedures on a 54 chevy fuel gauge with no luck and the tank sending unit worked just like you said yours did 0 to 30 calling Classic parts was not much help they did say the stem sticks out farther on the new gauges so watch for it rubbing on the back of the bezel.
To me the needle felt as if it were a bit sticky so with two nonworking new gauges i did something i would not normally do.
Thinking this just has a disk that spins and nothing to lose I gave it a 360 spin. Thats all it took it was no longer sticky so I hooked it back up and it now moves from 0 to full with no problems
Hoda thunk it.
I however had two new guages and nothing to lose at this point. Your mileage may very...
Ken