I have 1 1993 Yamaha 9.9 that starts hard. It will start & stall several times, once warmed up she is great. I noticed if I cover the air intake slightly while starting cold (like a choke) it runs better and will not stall. There is no hand choke on this engine.

Question, how does this engine choke to start as it seems like it is not doing so, what do I need to fix? thanks.