Yep, Kevin, I may have just wasted your entire afternoon:
http://hackaday.com/2011/08/30/engine-h ... lawnmower/
And the thread:
http://www.mytractorforum.com/showthread.php?t=136253
He talks about pulse widths. You love that.
And finally, a link to a forum dealinn entirely with this subject:
http://www.microsquirt.com/
Happy Labor Day weekend,
Ed