I have two Hondas on my boat, 225 hp, 2010, one motor reaches 5700 RPMs the other will not go past 4900
Things I have tried:
I have switched the entire fuel system, VST tanks, low pressure pumps, and cleaned all filters… No change in RPMs.
I have serviced the fuel injectors, and verified that they are all working when the motor cranks… No change in RPMs
I have verified. All six cylinders have almost exactly 200 psi in each cylinder… No change in RPMs.
I’ve installed new spark plugs… No change in RPMs
I am verified fuel pressure to the rail while operating and it is approximately 45 to 50 pounds… No change in RPMs
I have switched over the throttlebody assembly, including the intake manifold from one engine to the other… No change in RPMs
We have tried running the engine on its own tank directly to the engine,… No change in RPMs
I have verified that the throttle is working perfectly on both motors, and the same throw is noticed… No change in RPMs

I am about to check the oil pressure to see if this is not activating the VTEC… There are no codes showing

What is it that would limit the power to around 4900 RPMs?… It feels like it has less power even at the lower end.

I have to motors, so I can switch things back-and-forth…. I’m just running out of ideas of what to do.

Could it be an electrical connection creating all this nightmare maybe I should replace the wiring harness

Any help would be greatly appreciate it.

Glenn , South Shore of Long Island, New York