Mike:
Here is a wiring diagram for Smiths electronic gauges. My
oil pressure gauge works fine. The sender I have is the one listed by speedbrake above.
There are four wires coming out of the gauge:
Black - to chassis ground
Red - to the instrument light rheostat, for the light
Green - switched power (+12V)
White/Blue Stripe - to the sender
The sender has no ground, as it grounds through the threads. Be sure the sealant is not electrically insulating.
The gauges sweep through their motion when the key is turned on, then sweep back to zero. I don't have my car, so I can't do any tests or measurements for you at the moment.
Good luck.