I have had my 02 blazer since last april.....4.3 v6 vortec...... Ever since I bought this it has had this problem, honestly it is really just a pain in the ***. It takes between 10 and 20 seconds of holding the key foward before starting. Now once it is started it runs great, no other problems at all. Yet no one can firgure out this problem and ive given up, Id love to fix this problem though. Anyone have this same isues or has had it and fixed it let me know please thanks

 

First off, what have you tried?

Some suggestions:
1. Have you checked fuel pressure during a cold start up?
It sounds like when the engine loses vacuum it has trouble starting up.
Apparently, these engines need 56 PSI of pressure to start, anything under, even 54 PSI may cause trouble starting. The retained vacuum is what makes warm starts easier.
You could check the fuel pressure sensor, or perhaps the fuel pump.

2. When you roll the key forward and hear the fuel pump come on for two seconds, does it come back on while you're cranking?
It takes more than just fuel pressure to ensure the engine is getting fuel. The injector must be triggered on by the PCM. You need to have a good crank signal trigger to not only tell the computer to drive the injector, but to command the module to trigger the coil.
Hearing the fuel pump coming back on during cranking would tell you if the PCM sees the signal from the crank sensor.

 

Yikes...Id be scared to hold the key cranking for 20 seconds...

And yea just get your fuel pressure tested. Its probably low, which would indicate either fuel filter, fuel pump, or fuel pressure regulator.