I'm sure you've checked this but I know sometimes we look over the obvious stuff, is there fuel in the tank?

 

Last week, I gave my Blazer to my father for a weekend trip. Finally I need to pickup them because Blazer doesn't start.

Finally, fuel pump. But the issue was different as yours. In my case there ir a melted pin that cause all trouble. Since mine truck is second hand, there is a non original fuel pump assembly (imposible to identified, but seams a carter fuel pump) and a brazilian bosh fuel pump. I replace all cabling and the fuel pump works fine and hard: originally the fuel pressure doens't gave me more than 55 psi, now 60 psi . I also replace the fuel filter with a Wix, USA made filter (no chinese).

In your case, there could a lot of issues, but a bad hose from fuel pump discargue could be the main issue. Just in case, disconnect the fuel filter and take a look if there is fuel pressure. If not, could be a colapsed or broken hose (the ones that connect fuel tank to fuel pump are plastic and can be broken easy).
This applies if the fuel pump actually works (starts). Ask someone to go below your truck and try to listen for the fuel pump. If there is no noise inside tank, first check is there is dc current to the fuel pump: some cases if engine lube oil pressure switch is worn out, there is no electrical signal to fuel pump. Also, since dc cables runs below the rear end mat, some cable could be broken (heavy item drop just over the cables). In the rear end connector, as far as I remember, grey cable is the feeding to fuel pump. Check for DC power during start (found a suitable ground connection/black cable)

At this point, if not problems found, you need to remove fuel tank and take a deep look.

As far as I know, one main issue in Blazer /S10 series truck is a bad quality electric connectors. When change to the new Acdelco pump, take a look on electric connector. For me is totally recommended to change the electrical connector with the new pump. If not, could have a new "fuel pump issue" that could cost hard earned 300 bucks. Mine case I get it cheap: 3 bucks electrical connector, but more that 4 hours between removing fuel, removing tank, removing fuel pump, looking for the problem, reparing wiring, and reassembly. Without counting fuel and highway cost.

Finally, it could be "healthy" to test the proper operation putting 10 liter (or 2 - 3 US gallons??) in tank and try to start your truck with the fuel tank not installed (I used a rubber house for discharge and return, since the ones in your truck could not have enough length

If still no pressure... bad hose...

If you want photos for the melted pin, just tel me

PS: don't forget fuel tank pressure switch... I broke the cables when fuel tank cames off

 

I installed the AC delco pump and I could hear it run but no pump and I thought it was another bad pump like the china made one but then realized that with the china pump I had to switch the wire color around.
The Ac delco was running in reverse.
I swapped the wires back and presto!
Fuel pressure GALORE!
Fired right up first turn of the key and now runs like a kitten.
Never again will I skimp on such a important part.
Never.