1974 C10 Cranks for 15 seconds before starting

[lroberts2018]

My 1974 c10 takes longer than I want it to take to start. It will crank for a solid 15 seconds every morning before she fires up. Then throughout the day it will start fine. Any suggestions will be hugely appreciated.

 

[PrairieDrifter]

Sounds like the carb is leaking down for sure. The fuel pump may be as well, but that's normal after a week or so. My fuel pump usually loses prime on about day 4 of not being ran, I do have a return style pump though.

Any black smoke on startup?

 

[Vbb199]

Small Vacuum leak, or it's taking in a little water at the heads /intake/ valve seals I'd be willing to vote.