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Can anyone tell me how to check the OHM's on a fuel gauge and Sending unit..
I have 12volt fuel gauge (street rod style) and a replacement sending unit that works on both 6 volt and 12 volt.
The gauge reads 1/2 tank with only one gallon of fuel. It should read right at empty.
So I thought maybe the OHM reading might be wrong.
I am told the Ohm reading should be 73 empty and 10 full.
But I don not know how to check this.
Look forward to hearing from you guys.
 

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It would really depend on the brand of sending unit, GM style, Ford etc.....

Here some guidelines......

GM OEM style, If you remove the gauge and looking at the rear, there should be a resistor pack, bolted to three terminals forming a “V” shape. The upper left terminal is the sending unit wire, Tan on GM. The upper right is the switched 12v supply. The bottom center is the gauge’s ground.

Needle pegs full or past full – Break in the fuel sender wire (Tan) or tank’s ground wire is disconnected

Needle pegs empty or past empty – Break in the Gauge’s ground connection (under the dash)

Needle’s stuck in one place – Break in the Gauge’s 12v supply

Needle only moves to ¼ full – The resistor on the rear of the gauge is bad or has ground out to the side of the gauge housing.
 

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This might help?
It sounds like someone has given you the Mopar spec.

HotrodReference.com OEM and aftermarket Fuel Sender Ohm ranges

If you’re not sure of the fuel tank sending unit impedance, determine the resistance by following this method:

Disconnect the fuel tank sender from the gauge.

Connect an ohmmeter across the fuel tank sender. Connect the meters positive lead on the fuel tank sender’s output and the connect the ground lead to the fuel tank sender’s flange.

Manipulate the position of the float arm with a piece of wire or some other device so that you can position the float arm in the full and empty locations. It can also be done easily with the sender out of the tank.

Take the readings at the lowest (empty) and highest (full) readings. These are your fuel sending ohm range.
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GM fuel tank senders used 10 to 30 ohms until 1964 and then went to 0 (zero) ohms and to 90 ohms when full.

Ford fuel tank senders will read zero ohms at empty and 73 ohms at full.

Most muscle era Mopars fuel tank sending unit has a resistance range of 10-73 ohms.

Stewart Warner fuel senders are 240 ohms at empty and 33 ohms at full, although there is an “acceptable” variation of 10 ohms either direction.
 

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There is a tech tip on that "traditional hot rod" site showing how to make a simple tester for electric gauges and senders. It sounds easy,but I haven't tried it yet.
 

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Sounds like your sending unit took a crap easy way to check is to unplug it at the tank and short it to the chassis if the gauge says full your sending unit took a crap. if gauge still says E could be damaged wiring or burnt instrument panel transformer. OR you have to visit any good auto repair shop to fix it effectively.
 

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It's ......
Wire providing pwr to gauge (or the fuse to the wire etc)
Wire providing ground to gauge
Wire from the sending unit to the gauge
Wire for the sending unit ground (not the same as the gauge)
The Gauge
The Sending unit.
 
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