2003 2-stroke 90 - stall/starting issue

[longshanks]

Hi all- this motor's been a champ for me but has recently started stalling occasionally when at slowest idle speed, in neutral or in gear. It idles about as smoothly as a big triple should, at approximately 500RPM according to my tach... But has started stalling on me. And when I try to start, about 50% of the time it will fire but the other 50% I have to increase high idle setting to get it to fire. And sometimes when I bring it back to slow idle to shift it, it will stall out on me again.

Running quality fuel and oil in it and the plugs were changed out one year ago, or 10 hours ago. I've tried speeding up the idle screw but it didn't make a difference.

Motor has always been reliable for me and has even compression last time I checked. Any suggestions where to go from here?

thanks all.

 

[ondarvr]

You could probably adjust the low speed screw on the carbs and dial it in, but the carbs may be accumulating some crud and need cleaning.

 

[DavidMoore]

Not sure what you mean by "I've tried speeding up the idle screw but it didn't make a difference".

What idle screw did you adjust (low speed timing or carbs), and what difference didn't happen (still cuts out even if idle RPM is 650 to 700 as it should be or that the RPM did not increase).

Note Mercury recommend 650 / 700 RMP for a 90HP 3 banger, that it ever idled OK and stayed running at 500 RPM is impressive in my mind. I'm sure mine would not.

 

[longshanks]

Thanks guys. I hand-adjusted the 'idle speed' screw but the stalling/starting issue still persists.

 

[ondarvr]

Try adjusting the low speed screws on the carbs.