They used it for mowing but upgraded to a zero turn. They don't believe anything is wrong with it but have tinkered with it some and believe it to fuel delivery related.
/ Deere/Yanmar 650 - Trying to Raise From the Grave
As a further data point, I loosened the #1 high pressure line at the pump, and there is no fuel coming up into the line when cranking at full throttle. So the problem lies somewhere between the pump bleeder valve and pump exit.
/ Deere/Yanmar 650 - Trying to Raise From the Grave
I'll bet you don't need the pump. This is the same problem we face when we run it out of fuel. Crack all the injector lines at their tops a full turn. After 5 to 10 seconds of cranking a few dribbles of fuel will start to bubble out at the fittings. After a few more seconds, close one of the injectors and it will probably start to fire and spin faster. Then close the 2nd injector. It will bounce a lot after this but finally catch on after another 5 or 6 seconds.
/ Deere/Yanmar 650 - Trying to Raise From the Grave