Help, 89 25 hp 2 stroke won,t idle

Niko you need to start your own thread as this one is 3 years old. Since you reopened it what have you checked on your engine???

I had this exact same problem. I came across this thread in my google searches and it was never really "solved" so I thought I would contribute what I found in case someone runs across it in their google searches. My 1989 25 HP Mercury Mariner would not idle, didn't want to shift from forward to reverse or back and it would start only with a lot of throttle. I had near perfect compression, new plugs, filter, fuel tank, fuel lines and connectors, fuel pump, a carb kit, and about 40 empty beers. I was dumbfounded. So, somewhere around the 7th time I took the carb off to clean it, I decided to take the plate (#34) behind the carb off to inspect the reed valve. The Reed Valve Seal (#28) had pretty much disintegrated and what was left had turned into a pliable, black tar instead of a firm rubber. I believe this condition basically starves the motor of fresh air, at first only at idle and starting and it progresses from there until you can only start at full throttle and anything near idle speed kills the motor.

Part # for that is 85977 1 and costs about six bucks. If you've got the carb off, its so cheap and easy to replace and can cause you such a pain in the ass that I would replace it whether it needs it or not. You'll want part 41417 2 (#29) also since it will be destroyed when you remove the plate and what's left of the Seal. you can get 41418-1 (#33) also for the sake of completeness but I didn't use it. Hope this all saves someone some headaches. Thanks everyone for all you've helped me with as a lurker.