first of all i would like to say im sorry because im new here .
i have a 95 blazer - 4.3 vortec low fuel pressure at start up 48 - 50. i use starting fluid to get it running and the pressure jumps up to 60 - 62. this is completely back wards. any ideas what happened and what can i do to fix this ? already replaced the fuel pump, filter and pressure regulator, now just lost--plz help thank you

 

What is the leak down rate after the pump shuts off? Have you taken a peak inside the plenum to see if there are signs of a leak?

Check out the CPI thread in the Tech Article (DIY) Index link found in my signature.

 

leak down rate is low, not sure of the number. and i took off the plenum to replace the regulator. everything looks normal.

 

You can test the pressure at the fuel filter by connecting the gauge, through an adapter, directly to the fuel line that runs from the pump to the filter. If you get the same low pressure results there, then the pump is at fault.

The fact that the pressure jumps up once running leads me to believe that it is a spider/nut-kit issue.

 

i know what the spider is, but what is the nut kit ?
and how is this reversing my pressure

 

Engine running may partially seal up a leaking FPR?

The "nut-kit" is the name for the lines that run from the back of the intake plenum to the spider inside.