Gmc 2001 truck won't start

Make sure the battery is in good condition about 12.4 volts and higher. Then I would check all the fuses! Check to see if there is any engine codes!

Check to see if you hear the fuel pump engage with the ignition key in the, "on" position. That's before starting the car. If you hear nothing, troubleshoot the fuel pump. Check the fuse and relay then check the fuel pressure with a gauge. If you don't hear any fuel pump activation, there will not be any pressure reading. The relay will click when you turn the ignition to the, "on" position. If no click, switch it out with another relay in the fuse box to see if that works. If it does, replace the relay. If the electrics are good, you probably have a bad fuel pump.

I am driving a 2001gmcsierra 1500 4.3l v6 standard cab truck, new, starter, battery , cables, alternator, computer is in security shut down. Electrical. Why won't it start ??

Thank you, come to think of it, I didn't hear any click from anywhere. I will look into it, thank you, Leonard Linko.