By the sounds of it you need more diagnosis skill than you are available to give. Did you check for power and ground at the relay and the pump? If not, then those shouldn't have been changed. Clarify something. Is it a no start condition or a no crank condition? These need to be handled differently. I'm guessing from the info you gave already that it is a no start and that's what we will go with. Check to see if the relay is clicking with key on. If it is then go to the pump. If not, bypass the relay and see if the pump comes on. If it does the. You need to find out why you just have a problem with the relay. You should have two 12v sources, a ground, and an output to the pump. If any of those are missing then you need to find out why. A blown fuse would be an easy fix as would a missing ground. That's where ild start.
Also if there isn't power on pin 16 of the dlc then you won't be able to pull dtc's if there are any available.
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