35HP sometimes only running on one cyl.

Sesko357

Recruit
Joined
Jul 13, 2012
Messages
4
Hello all.
New to iboats and think its great!!

Here's my problem.
1989 Merc 35HP - Serial 0C104606

Usually this motor will run flawlessly. However, on occasion it will drop the top cylinder and run choppy.
When i remove both NEW plugs the top one is always soaked. I will clean both plugs, reinstall and MOST of the time she will fire up and run great. It is ALWAYS the top cylinder that fails.

When this happens, if i quickly go WOT she will stall.
If i slowly go to WOT she will bog like crazy but still run on the bottom cylinder for a while.... then all of a sudden run on both cylinders again. Sometimes this take up to 5 minutes to happen.

I have not swapped the coils over yet to eliminate that possibility. I guess my question is.... should i just go buy the switch box? I know its a common problem with these motors.
Does anyone have some wisdom for me??
Thanks
 

Sesko357

Recruit
Joined
Jul 13, 2012
Messages
4
Re: 35HP sometimes only running on one cyl.

Has anyone experienced similar problems?
Thanks
 
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