I prime my mower, it starts, runs for 2 seconds and stops. Why?

It's most likely not getting gas. Have you checked to see if the float is letting gas into the bowl? Gas line clear? Gas line and primer are not the same.

Hi,
Additionally, a dirty main jet not allowing sufficient fuel for sutained operation.
Peace,
Clarke

Thanks for the tips. Not knowing much about floats, etc. I thought I would remove the gas and maybe the tank to see if something is blocked. I've used the mower about 4 times.

The float is in the bowl under the carb.

Hi,
Often the main jet is in the piece that a 1/2" socket removes from the center of the bottom of the bowl. Not always, but sometimes. Can also be a swollen inlet seat, part of the part #398188 that does not allow the float to assume its proper lavel anymore.
Peace,
Clarke