After a few months of frustration we have finally gotten the Bobcat fixed.
Problem #1: The fuel takeup was all screwed up and jerry rigged. Fixed. This didn't solve the problem but it helped a little bit.
The bulb that you squeeze was hard as a rock. When I looked at the machine I realized...
My Bobcat 763 with a Kubota engine starts and then runs for ten or 15 minutes. Then it starts to sputter and smoke and then dies and is difficult to start. We have changed the fuel filter and that didn't make any difference.
Any suggestions on what to try next would be appreciated.