After some thought and research, I think I've figured out the 3 port setup.
This trimmer has no choke. Read the owner's manual, there is NO MENTION of a choke. Pictures in the owner's manual do not show a choke either. Because it has no choke, there has to be a way to richen the fuel-to-air ratio for a cold start. Enter the 3 port primer. In addition to purging air from the carb and fuel lines, it sends a small quantity of fuel into the carb throat via the 3rd port on the carb. (Or it may send air to the carb and actuate a diaphragm or pump that sends fuel to the carb throat.) Anyway, it somehow causes fuel to be put in the carb throat, regardless of how it does this. If you look at the position of the 3rd port on the carb, you will see that it is located up top near the carb throat, while the other two are nearer to the bottom of the carb.
Problem solved. :wink:
Feazels: Connect the fuel lines like I showed in my picture earlier. That should be the correct setup. :thumbsup: