Well after having the dreaded p0420 code on my 2002 blazer it finally got worse. I stalled out today and it will not restart, normally it would restart ..
So I am guessing it is the cat ,have fuel , spark ran great then on my way home bogged out no power .Am now sitting in a parking lot, will come back later cut the front weld off the cat and see if it starts any other suggestions guys? thanks

 

Distributor cap & rotor? Low fuel pressure? Both are common issues and both can cause it to bog down/no power and no-start.

 

Forgot to mention security light was flashing, can I by pass this?

 

Ahh, new information. There's your problem, and no, can't bypass it. Could be a problem with the BCM not recognizing the key. If it detects a theft situation, the BCM commands the PCM to shut off the injectors and you're dead in the water. You'll need a high end scan tool capable of accessing Passlock in the BCM to accurately diagnose the problem. A fairly common problem is the ignition lock cylinder housing with the Passlock sensor: Dorman Products - 924-713

 

went back to my blazer and security light now behaving, still wont start will be putting fuel pressure gauge on am beginning to suspect fuel pump can only
hear it faintly at the filler neck can't hear it while in the blazer

 

Well latest update on this is last night I cut a line in the pipe at the front of the cat , This morning it really wanted to fire up am getting popping and back pressure is this a good sign? had to bring the battery home to charge it

 

oh yes and did check fuel pressure it is 60psi when cranking and holds it so I believe fuel pump and fuel pressure regulator to be ok

 

ok sorry for so many posts but after 4.5 hours battery has not charged , no bubbles
and hasn't shown any movement on the gauge ,So guess it is time for a new battery, maybe the blazer will fire up

 

Fuel pressure really should be checked with the engine off and the pump running. That's when the pressure readings are the highest. If you got 60psi while cranking, it is at the low end of the allowable pressure spec. (60psi to 66psi)

"Popping", as in backfire or trying to start? Was the popping coming from the exhaust or the throttle body? Could be something as simple as distributor cap & rotor.

 

engine was off for fuel test, but with the battery dying gave it a crank to see wasn't much of a crank though, popping not sure where it came from my helper wasn't able ho hear right due to traffic