ExMark 52-in Lazer HP, 52-inch deck with Kowalski FH680V 23 HP.  Mower runs fine for 10+ minutes then the engine stops.  Seems like fuel starvation, fuel tank full.  Initially the engine restarted right back up and ran for a few more minutes.  Now after the initial engine shutdown it will only restart for a very short time.  Changed the fuel pump.  Fuel from tank flows good to the fuel filter but the see-through fuel filter is not full of fuel.