wow, that couldda ended badly. good thing you didn't go tear the neighbor a new one, lol.
that relay is pretty standard and used for everything from remote start kits to fog lights. there must be a current draw issue or you just got a bad or mislabelled relay.
ok, before I continue, don't get me wrong here, I'm not saying your truck was wired wrong or craftsmanship wasn't top notch. anybody could look at your build thread and say that would be a huge stretch, it looks factory for a newer car and the component layout is awesome. I'm just giving some ideas with the assumption that some first timers will also be reading your posts and someone may benefit.
I would start with: (don't turn the key on yet)
-check the wire size and length of run from the battery, through the relay and pump and out to ground, against the chart to ensure the wiring is large enough to safely support the current draw of the pump spec with some left over as a safety margin. ensure the ground in included in the dimension
-check wiring all the way back to the pump unit and to ground. looking for any heat issues where the insulation on the wire looks like it got hot. ensure the wiring is away from other heat sources as well, like exhaust etc. if there are any wiring connections in the run make sure to check them closely to ensure they are good for the current draw and are properly insulated and sealed (double wall shrink tube)
- do a draw test on the pump, separate from anything else. directly wired to the pump (through a fuse) where the relay was and also the amp meter with no ecm, relay etc. this will check the amp draw on the entire circuit from the relay back.
-do an amp draw on the pump where the wiring comes out of the tank and connects to the wiring going to the relay. I assume there is some sort of connection there and a length of wire running forward. this will eliminate any wiring issues, forward of the pump, and will let you know the actual current draw the pump is using. run the pump for a few minutes to allow it to heat up if it is going to. since you said the pump was making noise I would suspect the pump now, even though it may not have been your initial issue, because there are plastic impellers running inside plastic housings. once they run that long without fuel actually moving through them to help cool the parts they become suspect in my mind.
-compare the draw test against the pump spec and see how it compares
-pull the pump from the tank and check for poor connections inside the tank. I have personally seen wiring inside the tank with the insulation melted right off the wire.
-check the ecm circuit wiring diagram to ensure you know how that circuit is supposed to be wired, ecm supplies power to operate the relay or ecm supplies a ground to operate the relay, then check to ensure the signal wire from the ecm is doing what it should be with the key off. if it is not operating correctly check the wiring all the way back to the ecm. a cause may be a melted wire in the loom somewhere which is short circuiting a power or ground supply from another circuit into your signal wire which is turning on the relay. if there are no issues found with the wiring circuit it could be a possible ecm issue and would require testing on the ecm by itself.
-repair any wiring issues or pump issues. make sure there is a fuse, of the correct amperage for the draw from the fuel pump or as recommended from the pump manufacturer, placed inline on the power supply circuit before the relay. usually placed at the beginning of the power supply for that circuit. this can be, and often is, a "hot at all times" source in the fuse panel but this method can make the pump continue to operate if the relay sticks or otherwise malfunctions. if wired to a "hot with ign on" source your fuel pump would shut off immediately when the ign is turned off, whether the relay malfunctioned or not. this method does, however, place more strain on the actual ignition switch connections
-I always recommend the use of an oil pressure safety switch in the circuit if the ecm doesn't control that function or if using a carb style fuel system. this would shut down the fuel pump if engine oil pressure is lost. a good quality relay and proper relay plug terminal for the relay is a great idea as well. good quality crimp connection terminals, done with good quality crimp tools and protected with double wall shrink tubing is also a great idea. some crimp connections have solder inside as well as having built in shrink tube around the connection. this is awesome because it takes less time to do each connection plus the shrink tube always fits the connector properly.
if everything else checks out then one would assume the connection at the relay was possibly faulty and caused heat to build and may have caused the terminals inside the relay to weld together. this caused the pump to continue running even though the signal to the relay was off.
attached is a current draw/wire size chart from the net that I use and have had no issues with. maybe useful for somebody
here is a link to the holly page on fuel pumps. scroll down for a couple of ways to wire a fuel pump using the oil pressure switch. maybe useful for somebody as well
https://www.jegs.com/InstallationIns...0-12-801-1.pdf