2003 200hp hpdi wont go pass 4400rpms

[yamahaboo]

Please help
My yamaha has 600hrs and just replaced the fallowing and just stated to act up
Replaced strainer,fuel pipe joint,filter Assy.6 plugs,water filter 10 microns all this is done every 100hrs except the filter assy.i just usually change out the filter inside filter Assyassy.51 psi on the fuel pump filter assy.3/4 full of gas pump the primary bulb gets hard after 10 pumps but when engine is running after 10 pumps gets compressed and stays for a few sec.this is the new primary pump for ethenal.last 50hrs replaced both low pressure fuel pumps,vst screener and o rings,also 2 thermostats.can some one please give me advise I think the only thing I haven't replaced yet is the pressure regulator.

[rodbolt17]

me? long before I chunked parts at it I would test the medium AND the High pressure rails simultaneously AT the failure RPM and load.
the HP sensor can be monitored with a simple DVM and some paper clips.

[yamahaboo]

Thanks

Thanks for getting back to me I'll try it have a nice day and thanks again