Ok, my buddies 2000 Blazer died on him yesterday on the side of the road. I have confirmed that it is getting spark, fuel bleed down test was good, pump is priming when you initially turn the key on. It will start and run fine for a moment if you prime the throttle body, however it will not start on its own. I assumed that it was the passlock system but from what I remember that is connected to the radio and he has an aftermarket head unit. Any help diagnosing this would be appreciated. TIA!

 

Check the fuel pressure and report. Does the "security" on a dash lit?