I've just run the engine up to operating temp for the first time tonight, after getting the oil pressure and temp gauges connected.

Once up to full temp, the oil pressure gauge is basically at zero. The oil light is not coming on, and I have that connected now, so I would think that if there were no pressure I'd get an oil light.

Could this be a wiring or sender issue? It works ok when the engine is cold (or it did - haven't tried it yet after it was reading low).

I wired it without the condenser mentioned in the wiring diagram for the gas engine - could this cause low readings?