Hi , This moring I was sailing out of the harbor , arriving at sea I reved the engines and after cruising at 40 mp/h , abouth 1 or 2 minutes later , the starboard engine lost its power . When in neutral it would reve to 4.500 rpm , but I could hear that not all cilinders were workong , it sounded like a 4 cilinder.
Then i tried runninn a few minutes at 2.500 RPM on the other engine en opening the trottle a little more in the starboard engine , hoping it was only some dirty sparkplugs ?? but after 10 min. i gave up, it wouldend reven over 1200 rpm when in forward. So i checked the ecu for any DTC's (I have a small one with flashing led) and it showed code "12" so this means , no codes in ecu.


Oil pressure at 1200 rpm was 40psi , oil temp = OK , engine temp = OK too.

So far I have changed th espark-plugs , new cables , new rotor , new distributor cap , new ignition module in distrubutor , new fuel filter .......
So please help.............................

Carbs or FI?

Title of post says MPI so I'm guessing.....injected

You need to check fuel pressure at the small port on the fuel rail that looks like a tire valve.

sounds like a fuel problem.