Hey all, I've got an oil pressure problem with my GM 4.3 Vortec (96+). I recently dropped in a used motor into my boat. Hooked it all up and fired her up. Started up fine, good oil pressure, just needed to be timed and idle adjusted. Ran for 10 mins at fast idle then shut down. Went back next day to do timing and I had no oil pressure. Alarm going, gauge at 0. Stuck in a mechanical gauge into the sender port, still read 0psi. Removed motor as distributor and oil pump are not accessible while in boat. With motor on stand and my drill, priming it got normal oil pressure. What gives? Is it possible the distributor wasn't seated on the oil shaft properly? Any and all ideas welcome!