How to keep fuel up to the curb after shut off.

how long is a while?

That tidbit would help.

I had the same issue with mine, I installed a small draw through electric pump back by the tank. Turn it on to get the fuel up to the mechanical pump and it starts much better.

Also as mentioned, condition of the pump itself. If the diaphragm is leaking, that would be an issue. Are you smelling gas in your oil???