How should I test the fuel pump?

[Country Dirt Kid]

I am having trouble with my 1981 20 hp mercury. I am in the process of borrowing a timing light and a compression gauge. In the meantime I want to evaluate the health of my fuel pump. How should I do that? I already replaced all of the gaskets and cleaned the inlet screen. The only thing that I did not replace is the diaphragm because that did not come with that gasket kit that I bought. So how should I test the fuel pump? Thanks

 

[Alumarine]

Often when the fuel pump is faulty the motor will run well for a few minutes at speed and then come to a stop.
If you pump the bulb as it starts to slow down and the motor starts running well then that usually indicates that the fuel pump needs rebuilding.

 

[Country Dirt Kid]

OK thank you. It definitely doesn't do that. I can run it wide open all day and it fly's. thank you