Fuel gauge and grounding the tank? 1968 cj5 v6 225

Looking to install a new fuel gauge which I did getting 19 to 20 ohms from the resistor from the sending unit but I'm getting nothing from the gauge . I have the strap connected to both gauges, which I'm not using the temp gauge I'm using an aftermarket triple gauge temp,oil,volts which works perfect. My issue is the fuel gauge not moving at all. Omix sent me 2 gauges which I'm not complaining but just need one to work. Any suggestions grounding the tank which I tried with jumper wire. I'm just ready to put a jerry can and check the mileage. That's just the beer talking I want it to work. I tried to ground the tank nothing, all help is appreciated.
Thanks cj I'll post pics when I figure out how
All help is greatly appreciated

 

http://home.roadrunner.com/~john.strenk/Gauge web page/CJSpeedometerGaugeQuickTest.htm

check this out.

 

I had this problem and made some tests.

1 - resistance at the ground point : from the battery to the ground, the value must be very small, less than 1 ohm. If not the gauge will work badly.
The sender must have a ling to the ground. Check the value resistance between gorung on the sender and exit value.
Depending on what you have inside the tank this must be the value indicated by Omix for the dash fuel gauge.

The dash gauge is linked to the 12 v positive and the sender only.
You test it before mounting in the dash, connecting extra-wires.

The Omix dash gauge is bad quality so the current must be very perfect. TO much resistance and it is always going to empty.
And it is impossible to take off resistance. So the main ground must be perfect. The others too.
Well, at least it is what I understood.!