I have a 98 blazer 4.3 TBI 4x4. i have been having cold start issues, yesterday i hooked my battery up and it was giving about 11V. I used my mechanics bat machine and added a couple volts (total voltage about 13.5) and it fired right up. take the extra voltage away and it wouldn't start. after alternating this a few times it got to where it would fire up without adding the volts (typical to start fine after warm-up). I installed a brand new battery thinking it would solve my issue but didn't. fuel pressure at idle is around 52-55.
Ultimately i'm thinking its a fuel pump issue since my mechanic said its not the coolant temperature sensor. any thoughts would be helpful.

 

If a good battery wont start the truck it isnt the battery. I would look for bad connections. Grab a multi meter and look for voltage drop in the positive and negative cable. also check the voltage of the battery as youre cranking. You might be able to fix your whole problem with a piece of sand paper!

A good battery should give 2.25 volts per cell. 2.25 x 6 cells = 13.5 volts