Strange behavior
So you
* set the choke (one pump with engine off). It is closing all the way
* fuel does spray out with the pump
Does it start right away? With foot off the accelerator pedal?
If it is flooded it will only start if you hold the pedal down while cranking
On the other hand, if you have your foot on the pedal during a cold start, that introduces another variable. Best to get it start with the foot off
My guess is that the Choke Pull-Off is bad. As soon as it starts (foot off) the pull-off is supposed to open the choke approximately 3mm Otherwise the engine will start, and then flood out
you can test. with engine cold, and choke set, pull the linkage. Does it open 3mm? Good. Next pull hose off the Pull-off, pull linkage and put your finger on the port. Let go of linkage and it should stay. If the linkage goes back even with finger blocking the port, the
Pull-Off diaphragm is bad
Now that's just starting. If it begins to stall as the engine is warming up, the choke spring may be worn out an opening the choke too soon. You can swap on another Hitachi choke cover