As I understand your description: The engine starts and idles in Neutral,
but when you put in Forward or Reverse the engine dies.
This sounds like a fuel problem. I assume you have an external fuel tank
with a primer bulb inline with the fuel line. If you squeeze the bulb when
you shift into gear, does the engine still die? Do you have another tank and
fuel line? Verify the quality of the gas/oil mixture in the tank; water or
dirt will make the engine run poorly. If the problem is not external to the
motor I would suspect the carb has a blockage.

"mohm senad" wrote in message
...
hello

my yamaha 9.9 PS runs in coast problemles in max rpm.
as soon as i put in forward gear, it goes down to 1/3 rpm.

in backward gear is worse and it switches off.

any idea?