Okay I took my blazer to the dealer today b/c I thought my remote start activated the passlock. They tell me that it didn't and the only thing wrong is the fuel pump. I told them to bring my truck home and I'll fix it myself. How do I test the fuel pump? It is in a 99 model. PLEASE HELP!!!

 

Assuming it's a 4.3, Can you hear it running ? Hook up a pressure gauge to the fitting at the back of the intake manifold.Turn ON the ignition leaving the engine OFF, the fuel pressure should be 415-455kPa (60-66psi) when the pump is running.
If it's not running, you need to check for voltage at the pump or trace it back from there. Could be a fuse, fuel pump relay , oil pressure switch, pcm etc.. Trace it back with a volt meter because it's too expensive just replacing parts. The meter don't lie.

 

Mine went out on newyears eve on a 98 4dr 4x4. If you jack it up and drop the spare you can get under there and unplug the fuel pump electrical connector. Have a friend cycle the ignition switch which should send voltage to your pump. You'll get 12 vdc for a few seconds if it's good. I can't remember which connections to put the meter on but a Haynes manual has a picture of it. Good luck.

 

Before you do all that work, i was also told that my fuel pump went out or was going bad, what i did was replace the fuel filter on the drivers side, under the back door on the fuel line, and also replaced the fuel injectors and i was golden. Alot less work too...

however check to make sure you can hear the pump like prime itself first! and Filstoy is right about the voltage and PSI.