Mercury 100hp - rough idle and acceleration - Video posted

nwboater45

Petty Officer 3rd Class
Joined
Sep 6, 2012
Messages
91
I have been struggling with this motor to get it running smoothly. I have replaced plugs and wires. I also drained the fuel tank, replaced the fuel filter and water/fuel separator. Also have rebuilt the top two carbs. I have also gone through the link and sync per the service manual. After all of that the idle still doesn't seem to be right and it jumps a little at higher RPM's. Can anyone tell me if they think this is a fuel problem or if it is timing? I have posted a YouTube video.

https://youtu.be/0-xUWeK3gws
 

Teamster

Lieutenant Commander
Joined
Nov 8, 2010
Messages
1,923
Running those kind of rpm's without a load on the engine is bad for them,..

As far as I can remember those 2+2's ran like that,..

Only two cyliders are firing at idle and the other two start to fire when under power,....

How is it on the water?
 

flyingscott

Fleet Admiral
Joined
Apr 8, 2014
Messages
7,985
Why didn't you rebuild the bottom carbs if they are leaking you can have all 4 cylinders trying to idle. They don' like that
 
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