Trying to get the fuel gauge to work on my 68 rr sweep dash. I have a new tank and sender. I have the dark blue sender wire hooked up and the wire is good from front to back. I checked to see that the (regulator?) is pluged into the back of the cluster, and it is present. I also added an existing ground wire from the gauge cluster housing to a ground.

Any other things i should check? When i ground the sender wire the gauge does not go to full.