My 86' has had oil pressure gauge issues since day one. I have install a new motorcraft sender, single wire but the gauge still doesn't show pressure. Any insights can I tickle the sender wire somehow to see if its a wiring issue or a guage issue?

 

When installing the new sender, did you use anything to seal the threads like pipe tape? If not, good. The sender needs good contact to the block. Ground the wire and see if the gauge moves.