I had a '01 ZR2 Blazer that had the identical "40 psi key on, fuel pump prime & no start". After replacing the spider (was an upgrade anyway to the actual fuel injectors) and still no start except for starting fluid, I had to replace the fuel pump. The fuel pump was technically working, but the spider needs 56-58 psi to spray fuel.

Hope this helps.

 

There is another test were you hook up the gauge to the fuel filter which only tests the pump

 

That would have been awesome at the time! Good to know for any future diagnosis though