I’m not a lawn mower repair expert, but if you suspect the fuel pump and have a spare tank around, you might try using gravity to check your fuel pump. If you put the spare tank is above the carb, you don’t need a pump, that’s what gravity is for. If the engine runs fine from an elevated spare tank of gas, that would suggest a problem with your fuel pump, debris in the tank, or a vacuum leak.
As Sparky says, FIRST I would make sure I have a good vacuum to the pump. I would remove the vacuum hose if possible, check for leaks in the hose, then reattach the hose using a dap of compatible grease at both ends to get a good seal. Then try again.