I have a 2000 Blazer 2wd with 4.3l motor.

It takes an excessive amount of cranking to get it to start and once it does, it idles really hard, like its barely able to run. It drives fine and has plenty of power on the road.

I have 3 codes:
PO147
PO300
PO327

So far I've replaced the ignition wires and spark plugs.

Fuel pressure KOEO is 55PSI. When you turn the key on and it immediately jumps to 55PSI and immediately goes back down to 0. KOER is constant 48PSI once it starts.

Help?!

 

forget the codes for now, neither are causing your driveability problems:
Your problem is with the fuel supply, go here:
https://blazerforum.com/forum/tech-a...agnosis-23038/
Scroll down..
and do the at filter deadend pressure test.
You have to make an adapter with common parts

Alternative roll-dice short cut is Pull oil filler cap , see if you small gas. If so remove upper plenum and then key-on to see leak.
I THINK a plenum leak would not result in a 300, though. most likely a rich condition.

 

Update: I had to remove the battery to have it charged and when I reconnected it the car started right up and idled fine for a min. Started at 1100rpms, slowly dropped to 800rpms and idled really rough. Only code showing now is cylinder 2 misfire. Ideas?

 

Yeah.. you STILL have to do the FP tests.

302 could be plug wires touching ea other.

BTW... norm idle is 650. 800, warmed, means it's only idling that high to keep running.

 

The hard starting sounds like the fuel pressure regulator to me. If it pops up and then goes right back to zero that check might be shot. Also, the erratic idle could be a vacuum leak. With the engine running, spray the edges of the manifold and throttle body with carb cleaner and see if the engine smooths out. A vac leak can throw a 300 code.