Took first reading 45psi after it stabilized.
Will note that it took more than 20 seconds to get to 45psi. Second reading after 10 min. Was 36psi. Just for the heck of it I reran the pump again after getting the 2nd reading just to see the outcome. It still only climbed back up to 45psi.
Also the fuel filter has only about 4kmiles on it since I changed it last Oct.

 

I have to say I have used other forums and have not had as good luck as I have here. Thanks guys for your help.

 

45 psi is way too low. it must hit above 55 and hold. dont cheap out on the pump either. ac delco only. these blazers eat cheaper pumps like candy.

 

There is definitely a problem with fuel delivery, and this is what's causing the problem. The next step will require some "creative plumbing" on your part The pressure tester needs to be modified so it will connect directly to the fuel line at the fuel filter. All pressure and fuel flow from the pump must end at the tester. After you have it connected, do the same thing as before with the jumper wire. This time pressure must be 73psi to 108psi while the pump is running. It must remain above 55psi for at least 10 minutes after you disconnect the jumper wire. The results of this test will tell if the problem is in the tank, or in the plenum. Good luck. Post your results.

 

Thanks. Will do.

 

Followed your instructions. After about 30 sec. The psi from the pump got up to 84. After 10 min. Of setting the pump pressure is showing 65 psi. I guess the problem is in the plenum.

 

Ok here is what I done next. After completing the fuel pump check at the fuel filter I hooked everything back up and moved to the top again. Hooked the gauge up to the test port by the firewall again and turned the key on. It jumped to @30psi (I figured air in the line) and slowly started climbing and stopped about 60. Took about 10 sec. to there. So I started the blazer and it ran great for about 6 sec and then it threw the same fit it has been all day. But the higher pressure surprised me. While it was running smooth it was at about 53-54 psi. After sitting for about 10 min. It is still holding about 50 psi. I guess I'll start taking the plenum back off

 

Update- I took the carb. off and checked inside the plenum to make sure there weren't any lines going to the injectors that might be leaking. Checking everything at this point. Anyway I put the carb. Back on and tightened it down. Started the blazer and it sat there idled like there was nothing wrong with it. It didn't idle down or run rough at all. So I shut it off for about 5 min. And tried it again. This time it started and went back to the same old running rough and dying that it was doing before. Something around the carb. Has to be the problem. But it worked great and then not again is blowing my mind. I didn't touch anything between the time it was running and when it wasn't. Frustrating!

 

Ok after all of this I think I might have a sensor problem possibly. It will run now. Not perfect but not bad either as long as the breather is on. Take it off or even start to pull the breather away from through carb. and it will start to run rough to the point it will die.

 

The intake under the plenum should be black. If its gold and clean looking you have a problem with the spider. Also did you put a new gasket on the plenum