1994 50hp Missfires at Idle

[Aceman]

Runs well at all speeds above fast idle, new plugs but it missfires (with a high pitched squeek) and stalls. Sure makes loading a PITA. Where do I start looking ?
Thanks

[Ken]

Aceman,
I would try a shock treatment with Seafoam to de-carbonize the motor and clean the fuel system.
If that doesn't work, a carb overhaul is probably in order.
Good luck,
Ken K

[stevemon]

I have the same problem with a 1986 50. Seems to be "better" with high octane fuel but not really sure. I've rebuild the carbs twice with no luck there. If you find anything, let me know also. No mechanic seems to have a clue. It acts like a timing issue but mine is timed well. Maybe its a deeper problem with the powerhead. Steve

[Aceman]

Stevemon,
Checked compression 110 in all cylinders, manual said to test compression with engine warm.
Tried a can of Sea Foam Deep Creep. Aerosol spray. Followed directions. Ran engine at 2000 rpm 5+ minutes then sprayed heavily into all carburators until engine bogged down, almost stalled, billowed white smoke. Shut off let sit 5+ minutes and started again. Looked like a mosquito fogger. Ran 5 minutes at 2000 rpm and repeated twice. Problem solved.
I did put in plugs with one step hotter heat range to get electrodes to show that nice light chocolate brown color which is what you want.
Plan on burning nothing but high test in the future.

[carbuilder22]

I had a merc 60 with same problem, adjusted the slow speed mixture and idles pppuuuurrrrfect!

george

[stevemon]

Thanks Aceman. I'm running the seafoam in it right now. Seems a tad better after one tank. We'll see after two. I did not add it thru the carbs yet but will if I need to. Yee haa, I've been living with that for 4 years.