Originally posted by Kerrville Dan
I have exactly the same problem with my 85 HP Merc. Pumping the choke helps to get it on plane and then it runs like a top at high speed. Fuel filter is clean. Pumping the bulb isn't effective. I was just about ready to take it in for a carb job. Any ideas what might be wrong with the carb? Power pump?
Probably just dirt in the carb. It doesn't take much to clog the idle/low-speed circuits, so a clean filter doesn't necessarily mean that nothing got past.
Also, sometimes the source of the debris can be past the filter (piece of rubber from pump diaphragm, inside of line, etc...).