I have an 02' 35 lightning with the 575sci motors and when i reach ~4700rpms the port motor loses about 10lbs of oil pressure and the alarm light comes on. Any ideas?

What is the oil pressure compared to the strb motor? Idle vs 3000 rpm? Could be a sender or gauge?

The oil pressure is the same as the starboard motor up until ~4700/~4800 RPMs. Idle is the same for both and 3000 rpm is the same for both motors. We are thinking it's the oil sending unit. We unplugged the wire to the oil sending unit then plugged it back up. First pass at ~4900rpm was fine, no alarm light, second pass it came on again....

simple test swap sending units port to star and see if condition is the same ..

I think i know your problem....the oil pressure is dropping to its normal level due to all the freaking tanning oil those crazy girls were getting all over the boat!! Must have seeped into the oil fill cap!! LOL

My 02 Lightning w/575s did the same. At anything above 3000RPM for an extended period oil PSI would drop off 10# on one engine. Then after idling for a while it would return.* Oil pump had 200hours on it. I replaced it and the problem was gone. The pump looked cherry so I'd say it was a weak PR spring. I checked the bearings too....perfect. Now at 220hours the other engine is doing the same thing. I never got any alarms though.

Thanks! I will definitely look into this.