Fuel pump relay?

Youll have to check to see if pcm is sending a signal to relay. Or if shorted wire at relay box.

The sure-fire way is to pop the cover off the relay and squeeze the movable contact, but GM made that difficult with the design of their relays. Next is to unplug the relay and use a piece of wire or a stretched-out paper clip to jump the two wires in the socket. This is confusing because there's five wires in it instead of the normal four wires. The wires for the pump motor will typically be larger diameter and / or the connector terminals will be larger. Look for two of those. If you find three larger terminals, the third one would typically be so that same relay can be used in some other application. You should only find two corresponding wires in the connector. Connect those two larger wires to send current to the pump motor.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Here is the location and wiring diagrams for the relay. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

A couple of things I can think of, Check for primary voltage at coil with key off, engine running. Shouldn't be any primary voltage with key off, if so, my first thought is the ignition switch.

It could be dieseling, ignites off high cylinder compression, no spark, or a hot spot in the cylinder/s?

I haven't looked at your wiring yet, but, if there is an oil pressure switch wired in parallel with the fuel pump relay. As long as you have oil pressure, the pump can run, even if you unplug the relay.

Just to add, I'm not sure of engine litre size?

Do you hear the fuel pump come on? If so check the fuel pressure-pressure within specification-check for injector/s pulses

Check for power at the gray wire at the pump connector-power there check the ground circuit if okay replace the fuel pump

Check for a broken wire it's orange or the fusible link may have burnt up and it requires a new one. These are normally on starter but cold come from alternator.

Try this power the fuel pump connector from the battery and see if it will turn on.

I fyou have power on orange wire then it's the relay if not sending power to pump also when running it runs off of oil pressure switch. Scan for codes because it may be an ignition problem as tbi works only if getting a signal from ignition have module checked at auto part.

The computer might not be grounding the fuel pump relay coil side-also test the OPSU.