I just had this same problem. It turned out to be an airlocked system. If you have a hand vacuum pump ($25 at harbor freight if you don't) remove the outlet hose from your filter housing (the lower hose on the right side). Attach the hand pumb to the filter housing (the right angle port) and pump until you get clean fuel or hardly any bubbles (you'll need a clear portion of hose on the hand pump to see the fuel/bubbles). After you get fuel comming out of the filter housing, pop the hose back onto the port and do the standard bleed in the tech manual (gas cap open, vent on top of filter housing open, injector pump wire (pinky) disconnected). After I did this, it took about 15 seconds of cranking to get diesel to flow out of the side port (again, just like in the tech manual). After that, I had to pump the gas peddle a bit, but she fired right up!
If you end up needing to prime the system every time it sits, your fuel pump is probably bad. I pulled mine to check it...much easier to get at if you remove the passenger side alternator. If you pull it off, plug the inlet with your thumb and suck on the outlet. Cover the outlet with your tounge and see if it holds a vacuum. If not, bad fuel pump. $40-50 at any auto parts store, but CHECK IT IN THE STORE TO SEE IF IT HOLDS A VACUUM! If you find it's bad, you may want to hit a Chevy dealer and order one. It'll cost twice as much, it will work!
Like I said, I just got done fighting a similar problem. I ended up wearing out my starter gear trying to prime and had to rebuild it. Just pump fuel through the filter and bleed like normal.
Good luck!