Start up issue

[KellerMAC]

I have a recently rebuilt 72 C10 and it sits during the week and on weekend when I go to start it, I have to pump the gas pedal and turn it over for about a minute before it finally starts up - I drive it through out the weekend and it starts on first turn. Then when I let it sit for the next week, it's hard to start and we go thru the same process again. I have a manual fuel pump on it. Is there anything I can do so it is ready to start after a week long layoff?

Thanks,