Check the following:
1. I assume you are using the cold start properly. Advance to full
throttle and crank and immediately reduce throttle to about 2000 rpms. Once
running stable reduce throttle to idle at 600 to 800 rpms in gear.
2. Once running at say 4000 rpms in gear (not at the dock in neutral)
engage the choke.
a. rpms drop about 1000 or so - everything is correct.
b. rpms increase - you have a lean condition and need to rebuild the
carbs.
c. rpms do not change or change very little - fuel starvation problem
or ignition problem. Probably fuel starvation due to clogged vent in fuel
tank or fuel pump bad or fuel primer bubble bad.


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

"tom clark" wrote in message
om...
Our Merc 20 outboard is starting when cold and then stalling and then
won't restart. It doesn't appear to be flooding just turns over and
over. There is a spark in both cylinders. When it is warm it is fine
only when it is left for a while does this happen.

Is there a trick to the Merc choke /primer mechanism??