L Engine won’t go past 6500

[RJDriven]

New boat, took it fishing the other day, on the way home noticed it was yawing in one direction. Stopped, nothing in the cleanout, prop was free and pristine. Pulled it out of the water, jet looked normal.

Left engine gets to 6200-6500rpm then that’s all she makes. I’m thinking it’s a fuel/spark/boost issue. Boat has under 10 hours.

 

[Thermobrett]

Has it ever gone over that 6500 RPM? Check the oil level, if high, might be bogging down the engine.... Could be spark, does your boat require premium fuel, does it have super chargers? Mine requires 91 or higher octane due to the super charger and heard of engine performance issues when using lower octane fuel. Whats the RPM max on the STBD engine?

 

[RJDriven]

Yamaha SVHO engines, normally 8500k max. Right one operates normally. Oil level is fine. Worked fine last week but I was in 2-3 surf today and obviously it didn’t like the bumps.

 

[Judge]

There was another thread going about a guy with a single engine where he could not get over 22MPH and running at a max of 5200 RPM's. This seemed to happed after hitting a rogue wave. Some guys feel it could be an issue with the super charger.

That being said.... I have experienced low battery voltage causing issues with some of the electronic controlled systems on my 275SD like the Throttle (Throttle by Wire) and the Buckets (Buckets by Wire).... even when the boat started just fine.

You said the boat has less than 10 hours so if the batteries were sitting around for a while, they may be discharged and not fully charged. I'm not familair with the FSH boats but perhaps the left engine is not getting the command for full throttle if you have the Throttle by Wire.

I would disconnect your batteries.... give them a full charge.... then see how it behaves. My Throttles and Buckets were acting up and after disconnecting the batteries, charing them up and reconnecting all of my issues were gone. The boat had been sitting for a couple months and the batteries were not being maintained.

 

[lazergeek]

Bad spark plug or over filled oil can cause the RPM to be low.

 

[windshear]

Mine had a similar problem. Starboard engine got stuck once at 6000RPM. Engine would also surge after running over 30 minutes. Turned out to be the coil pack on cylinder number 1 hadn't fully clicked closed.

 

[zipper]

New boat, took it fishing the other day, on the way home noticed it was yawing in one direction. Stopped, nothing in the cleanout, prop was free and pristine. Pulled it out of the water, jet looked normal.

Left engine gets to 6200-6500rpm then that’s all she makes. I’m thinking it’s a fuel/spark/boost issue. Boat has under 10 hours.

We are talking about boats, nautical terms, Port side is the L or left side. Just being naughty. LOL