Fuel pump/relay issues?

[JoulesWinfield]

Hi guys, first post here but seems like it wont be my last.
We just recently acquired a 2016 Yukon XL 5.3l from my mom.
No history of fuel issues but last week (Been on the road for work all week), the wife was about to get on the highway and the Yukon just dies.
All battery function seemed fine, hooked up the jumper cables from my car just in case.
Basically we tried for a couple hours to get it to start. It sputtered and died once.
It was only about 85 deg, so not hot. Driving was on country roads about 15min prior so no stop and go.

Anyways, $200 to tow it home and I'm off to the airport a few hours later. I get back tonight to start diagnosis. Vehicle starts right up. Time after time no issues at all.
Scanner shows 3 codes.
Fuel pump high voltage, fuel pump open and an ECM voltage open.

Im thinking the open codes was when I was swapping relays under the hood to try and find the fuel pump relay. Never made any difference at that point.
However I'm thinking thise codes and the symptoms look like a relay issue, but why wouldn't the swap do something?

Does anyone know for sure where the fuel pump relay is?
Anyone have any historical fuel pump issues that sound similar?

Thanks in advance for any input cause I'm confused.

Joules

 

[Rocket Man]

Doesn’t the fuse cover on the 2015+ models list the relays and fuses like all the other years do? If not Im sure your owners manual does.

 

[JoulesWinfield]

Yes it lists them but no "fuel pump" relay is listed.
I believe it's the ECM or run/start relay.

 

[Rocket Man]

I don’t think it has a fuel pump relay but instead has a fuel pump drive module which should have a fuse in the under hood fuse compartment. Look for a fuse labeled fpdr or fscm for fuel system control module.

Edit: I suggest not pulling anything related to your Engine Control Module (ECM).