Just finished puttting together a rebuild in my fd. I have 0 psi pressure when the engine fires up. Is this a common problem after rebuild? I tried to do some searching but mostly found fc stuff.

Would not priming the pump cause this?
Is there a way to check the pressure sensor?

I also pulled the filter and it had very little oil in it. I did pull it after it sat for about 20 minutes but I feel it should of had more.

 

Assuming your assembly was proper and the pick-up isn't plugged etc., check the connection at the sender and/or replace the sender. I think there may be a way to check continuity to the gauge without pulling the dash.
Left for a few minutes most of the oil will drain from the filter.

 

Yep I would verify proper function of your gauge before going any deeper.

 

Looks like the coolant and oil connectors could be switched. I have the single wire that is connected to the starter harness connected to the pressure sender and the wire coming out of the engine hooked to the coolant sensor. Is this correct?

 

Did a lot of searching a found a bunch of stuff. Pressure switch is hooked up to starter harness and coolant to engine harness. Also grounded out the wire and pegged the gauge needle so the gauge is still working. The switch however is getting no resistance at all when hooked up to an ohm meter. Both when engine is off and on. So it looks like the pressure switch somehow went bad while I was rebuilding the engine.