2002 6.2 mpi mx lacking top end

[speakrdude]

Acquired boat last year and starboard 6.2 has always had a problem going over 4k rpm, and then slowly falls to 3500.
Engine was rebuilt prior to my purchase. Idles and runs smoothly.
Great oil pressure and normal temps.
Have never owned an MPI before or cool fuel type.
Where should I start?
Basic stuff? Plugs, wires, rotor, cap?
Or injectors, cool fuel area?
How to diagnose?
Have done basic maintenence.
Oil change, fuel water seperator...
Thanks,
Jim

 

[Bt Doctur]

Fuel rail pressure, filters, anti-syphon valve , electric fuel shut-off valve, spark plugs to name a few

 

[speakrdude]

Sounds like a service manual is in my near future.

 

[CliffA]

last year my starboard 6.2 would not go past around 4,000 rpms...problem was a bad fuel injector....

by chance do you also hear a 'knocking' sound from that engine that was not there before?.....my engine did have a knock that went away after the new injector was installed...

cliff

 

[speakrdude]

Havent noticed a knock. But I will listen closer.
How did you figure out which injector? Have them all rebuilt?
Thanks,
Jim

 

[CliffA]

Havent noticed a knock. But I will listen closer.
How did you figure out which injector? Have them all rebuilt?
Thanks,
Jim

had a mechanic use an analyzer to identify the bad injector...I tried unplugging one spark plug at a time while the engine was running at idle speed to see if I could identify a dead cylinder but the ECU made enough adjustments to hide the dead cylinder at idle....

cliff

 

[speakrdude]

Did you change out and was it hugley difficult?

 

[CliffA]

Did you change out and was it hugley difficult?

he changed the injector.....not sure how difficult it would be.....

cliff