1999 Suburban 5.7 Not Starting
 

This is my moms truck and she needs it for work i do work on cars as a hobby so know a little about a little. The problem started when it became increasingly difficult to start and after started would idle rough and sputter and now it wont start at all. While turning over there was a few times where it wanted to start but never actually did and when i would stop the attempt to start it would putt putt a few times. It had tune up not even a year ago so the plugs and wires should be good and it did backfire after several attempts to start so im assuming that means it is getting fuel. I hear the fuel pump kick on as well. Im thinking maybe ignition coil but am no expert can anyone help.

Another bad gas IMO

you think it just has bad gas in it

I just need some tips on what kinda tests to run to start eliminating things.

Whats the fuel pressure?how old is the fuel pump and filter?

i dont know how old they are she has had it for a few years and has not replaced it to my knowledge how do i check the fuel pressure

most auto parts stores sell fuel pressure testers and there is a fuel test port on the drivers side back part of the engine on the fuel supply and return lines it looks like a tire valve with a the key on engine off it should be 62-66psi

and what is the PSI is off what does that mean bad fuel pump bad fuel filter

It could be pump,filter or the regulator on the spider injector if the pressure bleeds down it could be the regulator or pump if you pinch off the return line and get better pressure its probably the regulator

The regulator and filter are the cheapest

The pump assy and spider upgrade are a couple of hundred each but the spider upgrade is a much better unit and comes with a new regulator the old spider assy was a crap design

what do I need to know before I do this because the manual that came with this testing kit is talking about disabling fuel pump and stuff like that what do I need to do