Your mower has a vacuum operated fuel pump. The diaphragm in these will give up. Some of the pumps allow diaphragm replacement, others you replace the whole unit. Check the fuel flow.
Sometimes the EPA fuel tank breather system gets clogged. After several minutes of fuel to flow out of the tank a vacuum forms and no more fuel will come out. Leave the fuel cap loose and see if that cures it. If so, find the breather and clean it.
Thanks for your suggestions for my friend's mower. It was the Charcoal filter. He cleaned it and the mower runs great. That saved him a lot of money and having to take it to the dealer.
Thanks again, Dave