No oil pressure reading on gauge?

[AnthonyG]

Fired engine up for first time with new bypass oil system
. I moved sending unit to a 90 degree take off at top of the filter. Pump & new filter sys. is working it filled it self with oil. It does have a reducing orifice about .090” supplied with the filter canister. Didn’t realize stud on the sending unit was loose so might have turned as tightening it. Thinking maybe the sending unit is shot?