Alrighty, 1999 Blazer 5-speed 4x4 88,000, the other day i turned my truck off to run inside, came back out to leave and it wouldnt start, noticed the fuel pump wasnt getting power, mind you i havn't had any previous issues truck was running fine no problems. Checked the relay , wasnt that...that was it for troubleshooting, which i regret now.....I went and got a new pump changed it out and it starts, i drove about 25-30 miles and the truck dies. Okay turn the key forward and pumps not getting power...thats odd, thinking thinking thinking, just decided to disconnect my battery, not sure why, reconnect battery and my interior LEDs turn on, idk if this has any relationship to this, and turn the key forward and truck starts right up, now this just happen about an hour ago so as far as has it done it sense, not sure yet, but im a little clueless as to what might cause this issue, oil pressure switch? not sure when i turned the key forward when it wasnt starting i could hear the relay clicking and a noise looked like it was coming from the top of the throttle body. I didnt disconnect the battery before i replaced the pump...possibly a mistake? Any ideas havent seen anything like this before...

 

Does the security light stay on when you turn the key to the 'run' position or does it shut off after a few seconds?

It is possible that you are starting to experience ignition switch problems.

 

Ah no it shuts off nothing different in the gauges i noticed the check gauges light came on for a couple of seconds when it stalled out after changing out the pump, but turned off right afterwards

 

I am having the same problem with my 95 blazer i put a pump in and it will start up and run fine but when i cut it off the pump wont cut back on. If anyone has ran into the same problem can you please go about telling me how you fixed the problem thanks