OK, problem solved. Hope this info helps.

I had Mechanic #1 check all fuel / electrical systems. He was absolutely certain it was the spider valve and estimated $600 for parts and labor.
Something didn't seem right. He was very pushy about the fix and dodged a couple of my questions. (For example, I asked if he was certain the alternator was operating correctly.) He was dead-set on the spider.

So I found another guy, Mechanic #2, who was willing to do an analysis for $25 bucks, in m y driveway. Found him on Craig's list. I didn't tell him the symptoms, just let him dig around for an hour.

He confirmed that the fuel pump and filter were good, fuel regulator was good, all electrical was good. He didn't even consider the spider.

Next, he bled the fuel lines, and the truck fired right up. First time in two months. No starter fluid, just a cold crank.

It now runs like a champ.

He did mention that 'old gas' can cause stalling and no-starts. I gave him an extra $25 and sent him on his way. Saved $550 by double-checking.

Can't say this will work for other Blazers, but it worked for me. YMMV.

 

That's odd... By testing pressure or just depressing the schrader valve in the fuel supply line, you had purged the air out of the line. Maybe it was just bad gas and you had to get more through it...

Hope it works out for you. Now that its running, I would put a double dose of Chevron Techron Fuel System Treatment Plus into the tank and drive it like you stole it for the first few tanks.

 

Roger that, haha.