No, normally i would test it first but i was in kind of s hurry so i just went ahead and replaced it. When itxwont start i have no power to the fuel pump but i do belirve i have spark. You can hear fhe pump come on after turning the key on and off for about ten minutes.

 

Don't guess at having something. Check it! There is no room for guessing in vehicle diagnosis. You actually have to get in there, run the tests, and let us know what the outcome was or we can't really help you.

If you don't think you have power to the fuel pump when it won't start, test for power & ground to the pump during a no start condition. If you have a multimeter, you can test whenever you like by measuring the resistance to the fuel pump relay from the fuel pump and from the fuel pump ground to a known good chassis ground.

 

I an hear the pump. Thats how i know when its going to start. When i turn the key to run it will only come on for a split second. After i cycle the ignition for a while it will come on for the full 2 seconds. The fuel guage goes to E when it wont start and a scan tool wont communicate with it either. I used a test light at the pump connector and it does the same thing the pump does. I apologize for not diagging my ignition switch first. What do you suggest next?

 

The fuel gauge going to 'E' when it won't start indicates that you have a grounding problem to the pump. Check the splice pack that the two black wires in the pump harness runs to. It will be located back near the fuel tank and have several wires running into what looks like a one sided connector. This connector is the splice pack.

 

Get a wiring diagram that is for your year of blazer. Brew a pot of coffee. get some colored pencils and sit at the dining room table. Try not to smack any body who asks why your coloring. Im dead serious here. this is the way i was taught to troubleshoot a wiring gremlin.

Start at the fuel pump. Trace the power wire from the fuel pump all the way back to the positive post on the battery.

Pick another component that doesnt act right. Does the radio work when it wont start? any other accesories? pick a new color and trace that all the way back.

pick another color. now trace all the grounds that feed those same components. What you now have is a very simple wiring diagram that isnt over whelming. Your problem is along your colored lines. If you find a common point where everything connects that is misbehaving, you have a potential spot to look.


NOW you can get up from the table. The reason we (work) does it this way is to avoid being tempted to jump to conclusions and start testing this and replacing that. You should be able to grab a meter (Or test light if you prefer. Right Swartlkk? LOL) and grab a buddy if one is available and be able to logically run through the diagram and find your gremlin. My guess it will be a loose connection on a pretty good sized wire.

just saw swartlkk's post.......he might be right. But if you do it his way you dont get to color!

 

No other accessories are inop. Do you know where approximately this ground is? Do i have to drop the tank? Its a two door with the spare tire inside the trunk. Thanks for all the help guys!

 

there are a bazzillion grounds. Get a good wiring diagram and it will show you where they all are.

I am not familiar with the splice pack Swartlkk is referring too. I own different years and have not had this exact problem.

BTW - Crayons work too.
Good luck!