Oil pressure

[Tinkerer]

Had a wierd thing happen last sunday - I allways fire the engines up for a second in the driveway before I go to the ramp. Starboard engine alarm goes off and there isn't any oil pressure on the guage. I shut it down and check the sender to guage wiring by shorting the wire at the sender to ground. The guage goes full scale. OK so the alarm and the guage are different circuits and they are both showing NO oil pressure. I figure that something failed as it fired.
I pull the distributor and check the gear , drive shaft and then put a drill to the oil pump with the drive tool. turn key on and it shows oil pressure and the alarm goes on and off with the drill. I put it all back togeather and everything works perfect.
Took the boat over to a SMALL local lake and run the engines for about 20 minutes and everything is perfect.
Have you ever seen this before?

[MILD THUNDER]

Thats weird. Did you happen to do a oil change or anything prior to firing it in the driveway? I know sometimes it takes a few seconds for the system to fill and build psi

[Tinkerer]

Oil change was done last fall. Boat was on the water three weeks ago and although not properly timed they ran fine. Idle was a little poor but they ran.

[Donskihp]

Sounds like an large air buble in an oil line,

[Donskihp]

Check all oil lines for leakage or moisture on them, any possibility the motor is a dry sump?