This is not a Chevy, but a close cousin. We went camping over the weekend, so my wife's 1997 Olds Bravada sat for 4 days. She was going to make a store run and it wouldn't start. It wanted to, but wouldn't. After some messing around, I poured some gas down the throttle body hole and put the air cleaner back on. it started after a bit and ran fine. Now it starts every time. It is a 4.3 with about 140k on it. Any ideas?

 

I would say very much so it can loose its prime, if the check ball/valve lets all the fuel bleed back down it could take some cranking to get fuel back to the throttle body, so much so you risk running the battery down...
I'd check the fuel pressure and if its not good strong and steady, it might be time for a new pump...
IF the fuel was particularly low it could have also lost its prime...