[Tfrazier]

So this is probably covered in a thread somewhere in here but I am not sure what to even look for.
Up to now, I have had zero issues with my generator (Kohler 12.5K). It has always started right off and has run smooth. 
This was not the case today. I noticed right off the bat that it was very sluggish when I tried to start it. It finally took hold and started then shut off. I tried again and the same thing happened. Strange.
I decided to start the engine and then tried the generator again. This time it started up fine and ran smooth. I shut the engine down and it  right on running (smoothly). I let it run for awhile and then shut it down. I gave it a few minutes then tried to start it again. Same thing as before (started then shut down). So I started the engine again and then the genny. It started right up and kept running after I shut the engine off. Anyone have any ideas as to what could be causing the problem? 

Thanks for your help.