Mercruiser Horizon 8.1 DTS RPM limited issue

[baddecision]

Hoping for some ideas as my engine guy has had no luck so far. Thanks ahead of time for any suggestions !!!

Mercruiser 8.1 w/ 240 hours. Last year had new manifolds and cool fuel unit replaced (due to paint on inside of cool fuel cover coming off) Stbd engine will not come up to full rpm, especially under load. At some point even with about a third of throttle throw remaining, engine power will not increase further despite more throttle added to limit. , no codes that we know of , warnings or faults. Compression, fuel pressure regulator, and plugs either new or check ok. My eng tech has also checked injectors and had them cleaned despite mostly clear. Fuel system out from Cool fuel unit to the fuel rails/injectors shows no blockages etc. No prop or shaft issues.

Engine still will not go above about 2900 RPM..(with the other at full throttle). .Prior to replacement of manifold and cool fuel on both engines, was getting about 4250 at WOT on both engines. Engine runs smooth but at a loss as to where to go from here in terms of troubleshooting to find issue..

Thanks ahead of time for any ideas!!

JT

 

[alldodge]

Howdy
Both motors were running good, and issue started with starboard motor after replacing cool fuel and "exhaust" manifolds

Said fuel pressure and compression are good, what are the numbers?

Will need serial number?
Do know if the throttle body is opening fully?

also checked injectors and had them cleaned despite mostly clear

What was done to check and clean?

 

[baddecision]

I will have to get the answers to the other questions, but regarding the injectors my mechanic pulled and they were sent to local place that cleans and checks spray pattern, 6 out of 8 gave the expected 85 CCs of flow, 2 were down to 70 CCs ..All are now 85 ccs and good spray pattern