After stopping to get fuel the vehicle would not start?

Does the security light flash when you try and crank the engine over? If so, the security system is enabled, you can use this guide to help reset it:

https://www.2carpros.com/articles/how-to-reset-a-security-system

When you turn the key on without cranking the engine over can you hear the fuel pump run in the tank for about 5 seconds? If not, you can help a defective fuel pump, or I would swap out the fuel pump relay which is located under the hood.

Please check out this guide:

https://www.2carpros.com/articles/car-not-running-advanced

Please check out these guides and get back to me, the fuel pump relay I have included in the images below.

Security light cones on with key but goes out like it should and stays off out a fuel pump relay in and pressure tested the brand new fuel pump i put in 2 days ago after cleaning the new fuel pump and replacing relay only getting 20 psi wait a min or 5 it goes up to 40 holds between 32 and 40 for an undetermined amount of time goes back down to 20 psi and sometimes to zero no rhyme reason consistency just random craziness I'm stranded in this thing 2 weeks now as i was moving 1400 miles across country everything i have is in this Tahoe i work on it and try to stay cool during the day and try to get comfortable enough to sleep at night its packed with all my construction tools and few things I have left in life I'm stuck on this private road / drive way until it is fixed I'm long out of money for parts therefore need to make what i have bought work all listed parts above i have replaced brand new in this 2 week time frame i do have another well the original ecm in one of these tubs wondering if i should try it if i can find it look forward to your reply and input. thank you

Sorry about your predicament. Do you have a new fuel filter? If so, it sounds like the pump has gone bad, here are the fuel pressure specs.

Key On Engine Off .................... 60-66 psi

Here is a generic guide to help you step by step with instructions in the diagrams below to show you how on your car:

https://www.2carpros.com/articles/how-to-change-a-fuel-filter

Here is how to change the pump out. Check out the images (below). Please let us know how it goes.