'02 BF225 Oil Pressure alarm

So, I fired up my 225 after sitting for 3 1/2 months and have been idling around the inlet for the last few nights with no issues. Today I took it into the Ocean and got the Oil Pressure Alarm when I got to 4000 or so RPMs. When into Guardian mode, so I turned it off and restarted. Checked oil and added about 1/2 quart. Tried it again and got the same result. Idles and runs fine til about 4k then shuts down.

Any ideas of where to go from here would be appreciated.

Confirm that the warning/protection slow-down is actually oil pressure caused.

You get the same alarm and slowdown from overheat and that would more likely coincide with 4000 RPM.

An outboard can easily suffer a spot overheat condition (often caused by a blockage within cooling passages) detected by a 'sensor', yet not 'feel' hot at all.
Art

Agree - did the green oil pressure light go out when the alarm sounded?

Yes, the alarm sounded and green light went out. Motor has new water pump, impeller, t-stats within the last 15 hours.

Well then I'd start with an oil/filter change. Look carefully at what drains out with a screen and magnet check. Also cut the Oil Filter open, Auto Parts Stores should have a special 'can-opener' for that as you don't want to 'make metal shavings' in the process.

Water contamination turns it milky looking and gasoline contamination thins it and can be easily smelled. Heavily gas contaminated oil would lose pressure, but at any RPM, and one cause of this can come from running too cold (like a stuck-open thermostat). But of course, this would raise your dip-stick level...

The sensor that completes the circuit to turn the green light on should be easy to access and an Oil Pressure Gauge could replace it temporarily to check actual pressure. Having normal oil pressure at low RPM and then losing pressure at high RPM is a mystery to me.

Confirm continuity of the wiring from the sensor to the light.

My Honda is just the little old (1986) BF-100 and to get access to its Oil Pump and Pickup Screen involves removing Powerhead and the lower part of the outer case serves as the 'Oil Pan'.
Art