Mercury 150 EFI Saltwater edition 2002

by Dennis
(Clearwater Florida)

I just purchased a boat with twin 150s. Both motors run great, but they will run at most 5 lbs of water pressure on the guage. I repalced both impellers with the full kit, body, plate gaskets etc with no change.

There is a telltale stream coming out of booth motors. They will alarm ( assuming overheat ) if left at full idle in a long no wake zone, and yesterday, we were cruising with a boat load at 4000 rpm and the starboard motor kept alarming and would drop cyls( assuming limp mods ) until I came off plane and started over.

These are fresh water engines with 400 hours on them and you can eat off any part of this boat.

It seems interesting that boat motors have the low water pressre. Is there a way to back flush the engine in case there is debris blocking something? I have also heard about poppet valves and thermostats but again, since its both engines I find that harder to believe although not impossible.

Any guidence is appreciated.

Thanks !