99 4 stroke running rough

"i have a mid 90's yamaha

"i have a mid 90's yamaha 9.9 4 stroke that has been giving me some trouble. It starts beautifully and will rev perfectly but in about 20 seconds it idles a bit rougfh and if you try to give it some throttle it craps out and almost stalls. If ytou turn it down it will idle but a bit rough. I have changed plugs, removed and cleaned out t5he carb jets, and used most of a can of combustuion chamber cleaner and I still have the same problem. The odd thing is that every time I start it it runs great for that 20 msec and then it does the same thing. Maybe a fuel pump?"

"I have the same problem. I ap

"I have the same problem. I appear to have overcome it dying completely by adjusting the idle screw to a satisfying position, but the engine still wanders at idle and even when in gear at low RPMs. Have you found a solution yet?"

had the same problem with my 9

had the same problem with my 94 9.9 4 stroke found the problem to be the intake gasket had a small crack in it.

ou have a fuel pump problem on

ou have a fuel pump problem once you prime up the carbys it will run great untill the fuel level in the bowl drops. Replace the fuel pump