Loss of RPM above 2500

[ronniemacd]

Got a 1989 Carver 3207 with Dual 5.7 gas Merccruisers. Engines run fine at 2500 RPM I can run forever. Go to 2800 on the Starboard engine and RPM drop right down nothing. Gas Filter changed, no change. No real change in exhaust except it smells like it is running lean on that engine.

Seems like fuel starvation problem or by reading here also looks like it could be plugs and wires or maybe weak fuel pump. Anyone here with a similar problem on a similar vintage?

thanks

Ron

[waybomb]

I believe you have two fuel filters for each engine. One spin on and one in the carb. Did you get both?
If so, I'd check the fuel tank vent screens.
And with the age of the boat, change the anti-siphon valves.
As a start.

[km1125]

Definitely follow Waybombs suggestions.

I'm curious though how you're smelling it "running lean"?? Is it just "not rich"?

[Torsson]

Clean the Flame arrestor with soap and toothbrush, let it dry good before you put it back. That got my engine running nice after i got the tip on this forum. The oil film that gathers around it will make the engine to not get enough air. Hope it helps

[Viper]

Could be fuel or ignition related. When was an ignition tune-up last done?