Fuel Tank sending unit, what type is compatable?

OK, seems that the new sending unit in my new poly tank doesn't want to play nice with my fuel gauge (GM type) which is supposed to receive 0 ohms at empty and 90 ohms full. What is the output in ohms for the CJ factory sending unit for 1980? If this is the correct gauge then my other thought is that the gauge is not grounded properly. It is supposed to be grounded on the tank but as it is a poly tank I grounded it to the frame rail next to the tank at the same spot I grounded the sending unit.

Did the 80's CJ's use a GM type sending unit?

 

Don't know about the '80, but my '75 uses a Ford sender. It's a reverse resistance curve, 90 full, 10 empty IIRC. Autometer has a good listing for most fuel senders.

 

I found this little gem of a how-to recently
http://www.jeeptech.com/electrical/gauges/
Maybe some answers in there

 

Great,,,looks like I need to order a new fuel gauge.