My port motor, (1998 502 MPIs) oil pressure needle bounces a little, from 40 psi to maybe, ~28-32 PSI @ idle. Oil pressure @ Speed is ~ 45-50 PSI rock solid. I've checked the oil pressure sending unit and it apprears fine and the wire is tight. The motors run and sound fine. Trying to figure out what's going on here.
The SB motor is a solid 40 PSI @ idle, and Oil pressure @ Speed is ~ 45-50 PSI rock solid also.
What do you guys think?
Thanks,
Dean

Not uncommon. Switch the gauge first, then the sender. It will likely be one or the other. If not, maybe the relief valve in the oil pump? My quess would be the sender or gauge or wiring. Been there, done that.

Switch the wires to use the opposite gauges and see if the fluctutaions stay the same on the same gauge or if the flucuations switch to the other gauge.

I had same deal, but one have one engine so couldn't compare. Ended up being the sender. I put a mechanical gage in to verify, but that was actually more work then just replacing the sender, but I am silly that way.

Had the same problem, ended up being the wire at the sending unit, had corroded. Cut it off, put on a new connector, problem solved.

I have the same problem...switched gauges and senders, and wires....didnt solve the problem. Whats next?

Put it in neutral and hold it wide open for 10 minutes.Should clear out the sending unit.

as long as you have 10 PSI per 1000 RPM you will be OK.

Thanks for the input guys. I'm going to try the gauge/sender swap and see what happens to the problem. This weekend's project is to modify my boat lift for the Nordic, so this will have to wait til next weekend.
Thanks again guys,
MD