I made the assumption that this was a diesel when you mention Westerbeke.

I'm not familiar with the model number you gave but from your latest
response and mention of "carb cleaning" then you must be dealing with gas
engine..

However, the problem still seems like a very rich fuel mixture, like running
with the choke closed or float level is too high or the float is stuck..
Rebuild the Carb!


--
My opinion and experience. FWIW

Steve
s/v Good Intentions