my 1990 yamaha 150 has been running perfect for along time. yesterday i was out and everything was good all day on the water then it was having a hard time getting on a plane and couldnt reach WOT rpms. it was lacking power and at WOT like a cyl or two was dragging. at WOT i could occasionally feel them kick in and i would get very short (split second) bursts of full power.
got home running on a hose and started pulling spark plug wires and it appears the bottom cylinder on each bank is not firing. im getting spark to both of them and the plugs looks great (nice and tan, no gas or carbon). when i pull the plug wire on each of these cylinders nothing changes in the way it runs whereas the other 4 do make a noticeable difference.
compression in these 2 bottom cylinders is also good. seeing as they feed off the same carb im thinking plugged jets but i think they have separate bowls floats and jets right? plus seaparate idle circuits right? seems wierd that both would go at the same time. any thoughts on this?
got home running on a hose and started pulling spark plug wires and it appears the bottom cylinder on each bank is not firing. im getting spark to both of them and the plugs looks great (nice and tan, no gas or carbon). when i pull the plug wire on each of these cylinders nothing changes in the way it runs whereas the other 4 do make a noticeable difference.
compression in these 2 bottom cylinders is also good. seeing as they feed off the same carb im thinking plugged jets but i think they have separate bowls floats and jets right? plus seaparate idle circuits right? seems wierd that both would go at the same time. any thoughts on this?