Makemyenginerun

Not sure why 85 will not get a power source. I know it has to come from the PCM. The internet shows many inputs that are required for the PCM to ignite or maintain relay power. The key word that they don't like to use is maintain or pre-ignition. The PCM sending 2-3 seconds power to the relay previous to cranking the starter is not a part of any of those maintain variables.
Things that maintain which i know don't matter at this point are
Tank pressure sensor
Fuel pressure
RPM input
We know the ground is there. What else does the PCM need to send power to 85? There are no fuses for the fuel pump and the ECM fuse is good.
Can something in the transmission cause an PCM to not send power to a fuel pump relay?

a55bruce

It's possible you have a bad connection at your fuseblock.
The fuel pump relay control is the Dark-Green w/ Wh wire at the PCM (connector 2 pin 9). Check for the 12V there.

Makemyenginerun

I did find on LS1tech.com the wiring diagram of the PCM for a 5.3L engine. Now I see that you are making reference to the 80 Way F Micro-Pack 100 Series connector to the PCM. At first I thought you were making reference to the back of the fuse block. So Pin 9 of C2 is suppose to be a dark green wire with a white stripe. I will look for that. On the back of the fuse block the PCM 1 fuse is the row 11 a pink wire and next to it is a big purple wire. Big because the wire insulator is thicker. Key in the on position No voltage there at all and it is the fuse marked PCM1. On Monday I will trace the wire back from Pin 9 of C2. Hey Bruce I just want you to know I appreciate your input. Chat Monday. I feel like we are getting close.

a55bruce

Look for the wire color (dark green with white stripe), let's hope there is only one.

Makemyenginerun

Print shows fuel pump relay at terminal A7 dark green wire with white stripe on fuse block C2. I'm going to be checking. The main thing I want to check is PCM C1 Pin2 which is 12 volt reference. Not sure if that is the main power for the PCM. Not sure what the 5 volt reference is for at PCM C1 Pin 7. How do they vary from Battery Positive Voltage on PCM C1 Pin 20?
My PCM fuse does not have voltage so I have to find out why. Once it gets voltage then I can check the dark green/white wire on Pin 9 of PCM C2 for fuel pump relay coil power. By the way this is where I get my print.
https://ls1tech.com/forums/conversio...rams-here.html

Makemyenginerun

Problem solved !!!!!
With the key in the on position I had no output voltage on the green/white wire to the fuel pump relay because there was no input voltage powering up the PCM to send output voltage. The under hood fuse panel labels it ECM. It does not receive power from a bus bar in the fuse panel tied to the battery. All of that lost power in its entirety goes through the ignition relay. LOL REALLY. Why can there be no mention of any of this anywhere I have no freaking clue.
So if you can't get fuel pressure with the key in the on position prior to cranking and you can jumper the gate of the fuel pump relay for fuel pressure but nothing with the relay in place, check power on the ECM fuse. If there is no voltage replace the ignition relay. Problem should be solved.