I found the inquire below from this forum that reflects the same problem as mine, but no good answers. Too many guesses. Please do not reply if you have not the experience on the exact problem.
"Like I said, It'll start with half a pull with a shot of starting fluid. After I have it running and I shut it off and then I try to start it right away, it'll start without any fluid, When I let it sit for 5 minutes or longer, then it will only start with a shot of starting fluid.
Pat"
I have the exact the problem as said here. I wish I can receive some direct answers with direct experience like Pat's. carburetor has been thoroughly cleaned. Pat, did you finally figure it out how to fix the starting problem?? thanks