1990 25hp Johnson running on 1 cylinder, plenty of spark, has good compression, spitting fuel at carb, suspect leaf (reed)valve. What is the best course to isolate the problem, pull intake?
If you suspect a reed valve take your carb off and shine a flashlight in there. You may have a small bolt or something that got sucked in there. You will see it laying at the bottom of the reeds if there really is something in there. Are you sure that you have a bright blue spark on both cylinders? You may need to clean your coil connections well.
plenty of spark?was this checked with spark gauge or the block.if you have narrowed it down to leaf valve,take the intake off and check the reeds.you cannot get a good sight with just flashlight.ends of mine were broke off and i couldnt see it.