248 Voyager prop question

[seasnake]

I have a 1996 248 Voyager that came with a Yamaha Carbureted SW Series II 250 HP outboard . The boat is a few months new to me . Both boat and motor are in Excellent condition however I can not get the motor to get over 4000-4100 RPM .The prop is a SS 14.250 x 17 . Motor is a S250TURU . I am not sure if this is a Prop issue or a motor issue that wont let me get over 4000 RPM. Any help would be much appreciated .

 

[ocnslr]

We purchased our Islander 270 new in 2002 with a 250HP OX66 (EFI). It had the standard Yamaha SWS 15.25" x 17", 3-blade prop. We could make the specified 5500-RPM when lightly loaded.

Is the boat bottom clean? Condition of the fuel?

Got to be something wrong, as you definitely should be running higher RPM on that prop..

 

[seasnake]

I am putting in new spark plugs, the motor is a 1996 I have no idea if they have ever been changed . The book says 4500 to 5500 max RPMs . There of course was fuel in the tank when I got the boat not sure about the condition but I did clean out the fuel filter under the cover and changed the fuel filter and primer bulb hose assembly . Motor runs pretty smoky at start up but after it warms up there is no smoke . I might get a chance to run it on Monday , will update after that .

 

[cgmiller]

Seasnake,

There are a handfull of tiny little filters associated with the fuel injection and VST system that are typically a yamaha tech job unless you are very well trained and know exactly what to do. They get clogged with the white residue from the ethanol in the fuel and stuff that gets past the spin on filters. My dad has a sinliar issue every 12-18 months, he starts losing power and the boat will not wind up all the way. You may want to take her to the local yamaha dealer and have it serviced instead of wasting a lot of time trying to trouble shoot things yourself...been there and done that...

 

[seasnake]

Fixed the problem .Before I could only get to 4000 RPM and then the motor would surge a little 300-400 RPM from 3600 to 4000. I replaced all the Spark Plugs and that fixed it no more surging .

 

[seasick]

Fixed the problem .Before I could only get to 4000 RPM and then the motor would surge a little 300-400 RPM from 3600 to 4000. I replaced all the Spark Plugs and that fixed it no more surging .

Did you happen to note if all the plug looked the same ( the firing end of course) or if one looked different. If one looked different ( was fouled) you may have something else going on that will eventually need looking into.

 

[seasnake]

They all had the same gap one looked a little dryer then the rest but none were overly oily or burnt . I am going to replace the electric fuel pump when I turn the key to the on position the pump makes a heck of a rattling noise . Other than that she runs good .