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I bought a 1998 yamaha 25 2 stroke for my 13 sport. Ran good for a while then developed a sneeze or cough. After researching I found this to be from a lean running condition. I went through all steps of checking compression, spark, check plugs, clean filters, check carb adjustments, check fuel pick up in tank and still had issue. I was just ready to start going into the carbs and fuel pump when I noticed the primer bulb did not quite feel right. It would pump but not get as hard as it used to. I disconnected the fuel hose from the tank just for kicks and behold, the fuel line is 3 part. A small clear hose on the inside surrounded by a black rubber hose and then the grey hose on outside. When the previous owner replaced the fuel line, when he pushed the hose onto the fitting on the tank, it pushed the clear inner hose into the rubber hose. Did not go in like supposed to. So, the clear inner hose was pushed in and bunched up in the line. Apparently it was letting just enough fuel through until I kinked the line by the fitting one day and it shifted the inner hose around and make a larger constriction. Also had a bunch of schmutz in the area from fuel reaction to something. Anyway, put on a new hose/bulb and problem solved. I know this is lengthy but may save someone time and trouble with diagnosing this on a 2 stroke.


(changed abbreviated year to full 4 digit year for clarification)

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Nice to know. Been battling a 2 stroke sneeze/ cough my self. I replaced the fuel line and I did notice the clear hose which broke off when removing the fitting.

Thanks for the heads up.