my son has a 2000 blazer with a 4.3 and i belive its a cpi. about a year and half ago we installed a new fuel pump and filter. two new fuel filters since last one about two months ago. the problem is if it sits for more than 8-9 hours without starting it is really hard to start the longer it sits the harder it is to start. no black smoke when it does start white or light grsy smoke instead. checked the fuel press at the shrader and it eas about 56 psi and lost 12-16 psi in ten min. ive read possibly the reg and spider but i dont feel comfy enough to dig that deep. whats the chances that my fuel pump is going bad or is there anything rlse i could try. it runs fine after you get it started and if you dont let it go more than about eight hours wiyhout a start help please

 

What fuel pump did you replace it with? I've heard if it's not an AC Delco pump or Delphi that they don't last very long at all.

 

You could dead head the pump with the pressure gauge at the fuel filter and if it bleeds off pressure like that then it's the pump.