An engine needs fuel spark and mechanical integrity to start and run. It must be determined if the cause of the engine not starting is loss of spark (ignition), or loss of fuel. It is easy to verify fuel pressure and delivery volume to see if that is the problem. If there is no fuel it must be determined if the fuel pump has failed or if the electrical circuit that controls the fuel pump has a problem. It's impossible to guess without being able to do some simple basic diagnostic tests.
If you own a GM product with the VATS or PASSLOCK security system, you are what I call screwed, I own a 1999 Chevrolet Silverado the truck starts when it gets ready, most days it will start right up but dies quickly, this is a sure sign the VATS or PASSLOCK is not working, I did a lot of research on this system and found only two ways of by passing the security system, the first way is to find the google how to by pass this system, you must remember in order to do a by pass you must determine if you have the VATS system or the PASSLOCK system, it makes a hugh difference, when you google and find the ways to do a by pass, this is at your own risk, I would recommend taking the vehicle to a good Audio and Sound center that installs alarms and have a Viper alarm installed and you won't ever have this problem again. Yes you could be having a different issue, but then if you don't get a check engine light or you can get your hands on a scan tool and don't find any codes anywhere more than likely you got issues with our Alarm. you must understand this system can involve, the instrument cluster, the radio system, the Body Control Module, the Engine Computer, it can even involve your door locks, just so you will know. have fun.
Thank you, I tested the fuel pump relay and it's working fine, and so is the fuel regulator. You could hear fuel flow before the fuel pump was installed last night, now you can not hear fuel flow. It appears as though the fuel gauge is not working now because it reads "low fuel". I have fuel in there, and only a little spilled out last night during the change. Do you have any more suggestions? Thank you so much for answering my question.