pressure regulator will not hold fuel to accurate pressure?

Hello,

First make sure all the hoses are attached securely and you do not have any leak.
It is possible to have a defective fuel pressure regulator.
Make sure the seal for the regulator is seated correctly.

This vehicle should have 60-66 PSI of fuel pressure with the key on and engine off.

Here is a helpful video:

https://youtu.be/aITQclp7zIE
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

I have attached the diagrams for your reference.

Please let me know of any questions.
Thank you.