temp gauge not working

I have read some older posts on this issues and tried the suggestions but to no avail. This is a standard gauge cluster in a 72 dart that has a new circuit board and the ivr is new also. I have made the temp gauge work I believe by grounding the sensor on the brass just below the threaded pin that the harness attaches to but if I try to ground any lower nothing happen, I am running a ld340 intake and I have the ground from the block to the firewall. The sensor is good as l get temp readings when connected to an aftermarket mechanical gauge.
I am also having trouble with the fuel gauge not working also. I grounded the sensor wire and the gauge went to full but when I tried to ground the sending unit nothing happened, I do not currently have the metal ground strap that bridges the 2 fuel lines.
So my question is could I possibly be having a grounding issue with the cluster?
Thanks