15 hp Mercury 4 stroke idles rough
 

I have a 2007 model Mercury 15 hp 4 stroke outboard here in my shop, we work on stern drives mostly but this little motor came in for service and looks to be like new still. Anyhow is starts and runs, but very rough and irratically. No mater where you set the carb, doesn't matter. Has new plugs and filter and carb are clean, just idles rough and even throttled up, doesn't matter.
Looking for answers and thoughts!!!

have you taken the carb completly apart, had a 2 stoke that went for a swim did the same thing . internal screan full of rust, just a thought:poopoo:

No and I will check that, thanks. The engine acts almost like it is firing intermittent on one cylinder. And I have never seen one snatch the pull cord from you hand like it is firing out of time or something, I guess this is possible, however everything looks factory. There is a mark on the wheel for #1 and #2 I just do not know where the line up point is. We do not work on these very much and I bought this one myself, always had two strokes and loved them.

have you checked that both coils are fireing. i had to replce one of the coils also after it went for a swim :daz:

Nope haven't done that either. It looks on the coil like it is a one piece coil with double wires coming out of it, most have two, especially on the two strokes. I will put my spark tester on and check that too.