So the engine turns over but it won't start. There's a replaced fuel tank, fuel filter, fuel pump, and relay switch. Maybe the spark plugs? But I can't seem to find them. Any help?

 

Testing for Spark at the Spark Plug Wires

 

any engine codes?

 

Fixed a ground wire on fuel pump, got it started but didn't last long. Any suggestions?

 

I had my blazer crank but no start and replaced fuel pump,Spider injector and still had intermittent crank no start everyone said replace cap and rotor with AC Delco.
I did and it starts every time. those cheap cap and rotors fail in a year or two so take my advise and get the cap and rotor from AC Delco

 

A couple. Start testing.

What is the fuel pressure and does it hold for 10 minutes?
Do you have spark at the plugs and is it a nice pretty blue color?

 

Okay so I tried everything you guys suggested and still no improvements. So I decided to just take it to a Mechanic and it turns out it was the Fuel Injectors and the Catalytic Converter. Thank you guys so much for your help.