rough idle - The Hull Truth

tterrien · 06-15-2008, 10:44 AM

02 mercury 200 carbed has rough idle and then stalls. Running it is fine but at idle it is rough and finally stalls out but starts right up. Just doesn't like to idle. Could it be dirty carbs,adjustments? I am stumped.

A1 Outboard · 06-15-2008, 01:16 PM

Most likely it is from varnish deposits from stale fuel inside the carbs, but other things such as engine condition can do the same thing. Usually it is the small passages for the idle circuit that plug up first. If you plan on dong the work yourself, get a factory manual first to get familiar with the components and their internals. Follow the procedures step by step.

Other things to check are the thermostats, recirculation system, the "sync and link" of the carb openings and timing, spark plug condition, and compression.

tterrien · 06-15-2008, 03:21 PM

how do I get rid of the varnish deposits? can I use carb cleaner?

A1 Outboard · 06-15-2008, 06:56 PM

Yes

tterrien · 06-16-2008, 11:38 AM

Another stupid question. Do I just spray in the carbs or do I have to take them off to do? If you can give a quick example on how to do it that would be great.

Thanks

A1 Outboard · 06-16-2008, 09:20 PM

Get a service manual, take the carbs completely apart, spray all passages and jets, follow the manual for assembly, and linkage adjustments. Replace pumps if needed.