6.2 mercrusier lacking power and won’t run more than 4400 rpms

[Thornton69]

I will tell you the engine that runs great does steam more than the port motor that would indicate a hotter exhaust temp.

Have heard of the wrong engine/drive being chased. It may be assumed the lower rpm engine is the problem when it is actually low having to work much harder. Am sure it isn't your problem, but have you compared hull speed to eng rpm while operating them individually?

 

[scoflaw]

Post #1 said you have a strong smell of fuel on port engine. To me that would indicate incomplete combustion.
I would still pull the plugs.

 

[Coy]

Well pulled two degrees pitch out of the port prop and now I’m up and running 5k rpms as I should. The starboard now needs some adjustment to catch up but it’s much closer than it has ever been.

 

[speakrdude]

Hope I can get my 2002 6.2s up to 5k!
Happy with outcome. Sounds really expensive!

 

[scoflaw]

So what pitch prop and what gps speed ?

 

[Coy]

Hope I can get my 2002 6.2s up to 5k!
Happy with outcome. Sounds really expensive!

You running v drives or out drives?

 

[Coy]

So what pitch prop and what gps speed ?

I’ll have to check with prop shop for actually degrees on each side. GPS speed 30 mph. From what I read that’s all they do with v drives

 

[Motoguy2158]

With all you've done it seems like its an external issue, meaning not the block, pistons , injectors etc.
How about fuel tank, fuel lines, fuel filter.... Something pinched or obstructed on the port fuel supply or air. Did you clean the Flame arrestor. Mine was completely blocked when i got my boat. Soaked them for days with brake cleaner to get them clean. Switch fuel lines from port to starboard to see if somethings going on like a blocked vent. I had mine plugged with spider nests one time and it wouldn't take gas without spitting back at me when trying to fuel.
Just throwing some things out that come to mind. Sound like you been on long journey.

 

[StefanFL]

I would try to swap props and I'm positive, problem will occur on starboard with port prop.

They might be repaired and have same pitch, but due to previous damages machining might took more material of starboard prop toward the edges, so it provide more slip and engine is get chance to spin easier up to the rpm where it makes more power.

If it's the prop, I would replace both prop with news. engines will run smoother and last longer.

Also double check recommended WOT, 5200 seems too much for inboard.

I know for 7.4mpi same engine, recommend wot for sterndrive is 4200-4600, but for inboard 4000-4400.
Might be the case with 6.2 as well.

Also double check wot rpm for both engines with shop tacho, if they overrev, they might drop valve again.