Yamaha 212x rpm issues. Help please.

[dadofral]

Been awhile since I posted as we haven't been boating that much. Short story is that my wife and kids had our 2008 212x out a couple days ago and the boat ran great. We are out today and at idle both engines run about the same rpm. When I throttle up the port side engine will hit about 7000 and the starboard only hits about 4200 and fluctuates up and down. Any ideas why this happens all of a sudden? I replaced the spark plugs last year and I also checked the clean out plugs and no leaks or debris. Any help is appreciated.

 

[itsdgm]

I'd start by changing the spark plugs again and maybe taking the battery in for a check.

 

[dadofral]

The plugs came to my mind too. What would the battery have to do with it??

Simone else suggested the ecu possibly. But I hope not.

 

[Scottintexas]

any other unusual noises or vibrations? I'd start with the plugs also,

 

[Scottintexas]

It could be the battery has a loose ground or not fully charged and is causing an intermittent issue,
The ecu could be an issue but it would be further down the list, try the plugs first

 

[dadofral]

Lolita first. Maybe a new battery too. Thanks all.

 

[SamCF]

I don't know much about the twin engine boats, but you could swap the ecu's and see if the problem follows to the other engine. I highly recommend getting the YDS cable and software. You can check engine codes, and read the output of all of the engines sensors. I made a longer cable for mine so I can watch the ecu outputs while I drive the boat.

 

[Evildwarf]

Lolita first. Maybe a new battery too. Thanks all.

Reading Lolita may not help your boating issue.....

 

[Julian]

I check things in this order:

1. Battery connnections
2. clean out hatch kills switch (tape a coin over where it hits the lid for the starboard switch)
3. unplug and replug the lanyard a few times
4. change the plugs
5. test the battery(this seems like a long shot at the port runs fine....does the starboard run ok with the port engine off?)