fuel gauge ground issue

[RJH]

I have a 70 non rallye fuel gauge that did not appear to be working. I removed it from the cluster and it works if i ground the body of the gauge. My question is , Is one of the studs on the back of the gauge is not a ground stud. Also my gauge with 4 volts supplied the the one stud only reads 3/4 full . Is there a easy way to calibrate the gauge itself. Thanks

 

[Adam]

There is a short piece of rubber hose where the fuel line connects to the gas tank, there is supposed to be a jumper strip bridging that rubber hose. See if that is in place...

 

[Steve340]

I believe the gauge itself has no calibration. What voltage are you getting from the cluster regulator?

 

[Mopars & Missiles]

There is a short piece of rubber hose where the fuel line connects to the gas tank, there is supposed to be a jumper strip bridging that rubber hose. See if that is in place...

Here's what Adam is talking about.......it's called a "ground strap".

 

[RJH]

Thanks guys.I know about the grounding strap on the tank . I was bench testing the gas gauge. it was removed from the cluster. I found a broken wire on the bi-metal strip. Also the power into the gauge was grounding out to the housing . What a shame as it was a very clean unit. I had another gauge and combined the two into one unit. This unit will only read three quarters of tank with 4.5 volts.It should read full. As a millwright I know every thing mechanical must be able to be calibrated. Here is a couple of pictures . The arms with cut teeth at the ends and accessible through the little holes on the back of the cover is where I think you calibrate the gauge. I will attempt this, in the morning and let you know how I made out. thanks for all your help

 

[cudamark]

Thanks guys.I know about the grounding strap on the tank . I was bench testing the gas gauge. it was removed from the cluster. I found a broken wire on the bi-metal strip. Also the power into the gauge was grounding out to the housing . What a shame as it was a very clean unit. I had another gauge and combined the two into one unit. This unit will only read three quarters of tank with 4.5 volts.It should read full. As a millwright I know every thing mechanical must be able to be calibrated. Here is a couple of pictures . The arms with cut teeth at the ends and accessible through the little holes on the back of the cover is where I think you calibrate the gauge. I will attempt this, in the morning and let you know how I made out. thanks for all your helpView attachment 48553 View attachment 48554

You need to include the sending unit, voltage limiter, and wiring harness in your calibration attempt. Those other items will effect the resistance in the circuit and therefor the calibration.

 

[RJH]

That's actually makes a lot of sense, Thanks every body for all your input. I'll find just how accurate my calibration is, when i run out of gas and the needle shows 1/8 tank