You probably need to tear down and clean the carbs.
How long has/did it set before it started this?

--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

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"Chuck H" wrote in message
om...
I've a 50 HP Merc 4-stroke outboard, model year 2000. Location is St.
Peterburg, FL. Recently it has been "coughing" every 20 seconds or so.
Sort of like it misses a beat regularly. Seems pretty regular and to be
the same at all speeds. Doesn't really cause a problem except that at
idle speed it often causes the engine to die which is a real PITA when
docking, although it restarts easily. I've emptied and refilled the gas
tank and changed the fuel filter ... no joy. I changed the spark plugs
last November and there's probably only about about 100 hours on the
engine since then. (sailboat).

I've considered just increasing the idle RPM to get rid of the 'dieing at
idle' problem but that wouldn't really solve the 'coughing' problem. I'll
certainly appreciate any advice you engine people may have.

Chuck H.