So with the scan tool telling the pump to run it works fine?
Is it possible that the computer has a bad ground and is not supplying enough power to the pump relay to keep it activated?

 

sorry didn't see that the thread wen't to second page. Will check the ground on the pcm. What I have done is change the badly cloged air filter also the pvc valve also changed the spark plugs found 2 to be partially fouled others apeared normal but worn. Don't know if this will help diagnose but I live in ne pennsylnania, and temps here have been cold latley.

 

went out to work on the blazer swaped the two relays in the glove box and now the pump wont run switched relays back. still nothing. pulled relay checked voltage 12.4 volts to hot side of relay. the relay clicks when turn key switch on but no pump noise. Got the scan tool out and forced the fuel pump relay on but no pump noise. Could the pump have been the peoblem all along? It was working I had pressure guage on the fuel port earlier. Could a bad connection be the problem? Either way it looks like I'm going to lower the tank and see. Now is when I wish for Summer.

 

The next thing to check is whether you have +12v to the pump connector.

 

Will be sure to check prior to cracking open the tank. Picked up new pump strainer and electrical harness today hope weather is good this weekend.

 

I just went though about the same thing. Pressure was good when running but sometimes to low during cranking and would not fire, above 50 psi during cranking and it would start.

Finally the pump stalled and I replaced it with the Delphi pump and our blazer starts like new.

Here is my story.
https://blazerforum.com/forum/2nd-generation-s-series-1995-2005-tech-41/my-hard-start-excessive-crank-story-37447/

Blazeme

 

Got tired of waiting for nice weather and went ahead and braved the cold.
While removing the fuel lines the flange connector was rusted to the fuel line hence broken sending unit fuel line. Changed it and pump. Checked for power at plug was good. reinstalled tank put in 2 gal gas to try it. Engine cranked and started first try. Thanks to the replys here on the forum and my new haynes manual. Repair manual should be part of the standard options of every vehicle.

 

Glad to see you are starting again. The fuel pumps do seam to be able to work part time and not always deliver the right pressure during cranking. Hope thats the end of your problem. Mine is still starting great so far

Blazeme

 

I knwo exactly what it is. Under yor plentum there sets a "spider" injector. This regulates the fuel to 6 poppet valves. Take the plentum off and check continuity between the terminals. If they read open, your not getting the signal for the fuel to deliver. I fought this problem for about 2 weeks. This injector is probably going to run in the 'hood of $300 with a technical difficulty of about a 7.
Good luck and let me know how it goes