Engine not starting

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.

Check the harness in the grren wraped tape on the right side of the vehicle under the rgiht kickpanel, and the gray wraped wires on the left side.

Was your master cylinder replaced recently?

This guide can help

https://www.2carpros.com/articles/car-cranks-but-wont-start

Please run down this guide and report back.

This may indeed be a dealer-only problem. The engineers at GM have cleverly designed in a number of things that require trips to the dealer. Some problems can now be handled by independent repair shops, but only once the aftermarket industry develops the very expensive specialized diagnostic equipment. All GM owners go through this. The same is true for BMW, Audi, and VW owners. All of those companies have an abundance of customer-unfriendly business practices such as these.

What you can do is start by checking the fuses inside and under the hood. At first I thought the engine died when the head lights were on while you were driving, (which is another common GM problem), but I think you meant you left the lights and ignition switch on when the engine was not running, and that ran the battery down. If that is correct, it is fairly common for a few fuses to blow simply from connecting jumper cables or a battery charger. That is from the current surges that occur, and there is no other actual problem.

One problem I have been running into is there are a real lot of fuses now, and they are no longer labelled for the circuits they protect. That is because they usually feed computers that run those circuits, so a fuse might be labelled "IPC 3", "TIPM 5", and things like that. You do not know what those mean? Welcome to our world!

Instead of trying to figure out which fuse to test, use a test light to test all of them. If you do not know how to use a test light, get hold of one, then I will explain it. All of the small spade-type fuses have two tiny holes on top for test points. Turn the ignition switch on, then test for voltage on both test points for each fuse that you can. If you find 12 volts on both test points, that fuse is good. If you find 0 volts on both sides, that circuit is currently turned off, and that fuse is not in a circuit related to this problem. You are looking for a fuse that has 12 volts on one side and 0 volts on the other side. Replace any that are blown.

The larger cartridge-type fuses have to be checked visually through their clear plastic covers, but those are much less likely to blow from connecting jumper cables. If all the fuses are good, the dealer may need to unlock some of the computers. Needing to do that after simply replacing an old battery is a trick that's real common on VW vehicles, and GM copied that on some of theirs too. Running the battery dead causes the same problems, if any, that disconnecting the battery to replace it causes. The aftermarket industry has come up with a whole bunch of "memory saver" devices that allow us to replace the car's battery without needing to tow the vehicle to the dealer to have those computers unlocked.

Hello,

Here is a link to an article form this site that features written step by step instructions and pictures explaining how how to use a test light.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

If you need further assistance please come back to the site we are always happy to help.

Thank you for visiting 2CarPros.com.

Kindest regards,

Renee
Admin

Based on your description, it sounds like you may have a bad fuel pump. Have you checked fuel pump pressure to see if it is within the manufacturer's specs?

First thing do not take auto advice from a parts guy they only sell parts and are guessing every ting else. try resetting security system because of battery problem. see picture for instructions GM changed security resets around the time of your truck so it may not work. If not look online for your truck on how to reset it. then check fuel pressure with a gauge auto parts rent that. but sounds like a securtiy problem. which any garage mechanic can scan and find out if it is then if something is messed up he can fix it.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Just to add to this one it sounds like the body control module is going bad. You said it had plenty of gas, but read empty and would not start. Those are common symptoms I used to see when I worked for Saturn and that would happen when the body control module went bad. I have seen them suddenly fail from jump starting the battery. Battery going bad or running the batteries down like you did. So keep an eye for weird things not working or acting strange. The body control module controls a lot different things.

You're right. The fuel pressure is siphoning back into the tank.
There is a check valve in the fuel pump to prevent that so it likely needs a new fuel pump.

50 PSI is just not enough for that engine. The spec is 60-66 and usually won't even run below 55.

The filter will never be the sole cause of a performance problem, however it can damage the fuel pump by working it too hard so it should always be changed along with the pump.