Starboard engine issue

As the subject line states, I am having a problem with my starboard engine (Mercruiser 350 Mag MPI). I can get engines up to 4K rpm on both engines getting on plane. As engines heat up seeing the psi drop to 4.5 on starboard side, 5 on port side. Engine falls back to 3400 rpms and won’t go higher. Sounds fine, temps are fine.

Any thoughts on what might be going on?

I did take boat out this morning and ran boat hard in reverse to shake anything (hydrilla) that could be on prop.


Thanks for tour help!

kevin


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low water pressure can put the motor into Guardian mode

Checked strainers, all clean. Water flow appears good.

When you say the psi drops to 4.5 and 5 are you talking about oil pressure? The minimum oil pressure for a 350 Mag engine is 4 psi. It may be going into Guardian mode because of the low oil pressure. What oil are you using? The recommended oil is Quicksilver 25W-40. Alternatively a straight 40W oil can be used. A friend of mine bought a used boat and was having low oil pressure issues. He found an empty bottle of 5W-20 in the bilge. Once he switched to the correct oil his oil pressure was fine.