97 Challenger Fluctuating RPMS

[Tend2bebroken]

First off I'm new to this forum and boating so thanks in advance for any help.
I just purchase a 97 Challenger which was supposed to be in good working order just summerized by a sea doo mechanic. Took the boat out last week for a quick spin ran fine. Went out yesterday ran about 20 minutes felt fine when all of a sudden RPMS started jumping. When at idle the boat sounds fine when any throttle is given it fluctuates between about 2 and 5 grand. Changed out the plugs. Both plugs looked very dark like they were running rich. Unfimiliar with boats but have been building cars for awhile so i'm not to scared to rip into things but would appreciate some direction before i go tearing into things.

Thanks,
Dan

 

[Dr Honda]

On a 2-stroke... dark plugs are normal. Fluctuation is not.

I'd say you have a fuel supply issue, and most likely you have a leak in the fuel select valve, (draws air if there is a leak) or it's just time to clean the carbs.


Is it going to full throttle, or is this just a mid RPM issue?

 

[Tend2bebroken]

Thanks for the quick reply,

Where is the fuel select valve located? The fluctuation seems to be at all throttle points. Is there a good rebuild kit supplier for these carbs? I figure if im going to take them apart I might as well rebuild them while im in there.

 

[Dr Honda]

You want OEM Mikuni rebuild kits. The import kits are having issues with the main diaphragm. I normally look on eBay, and find the best price.


The fuel select valve is where you turn off the fuel, or switch to your reserve supply.

Where in PA are you?

 

[seadooya]

fire boat up, and while holding a steady 5500rpm, or as high as you can get it, but not past that rpm, volt test the battery, should get 13.5-14.5v, if in 15's or 12's, replacethe rectifier...