The fuel distribution in my 747-8i in MSFS is repeatedly insufficient, with the FMS complaining “insufficient fuel”, and my outboard engines keep running out of fuel mid-flight (thankfully I have failures turned off)
Are you configuring the fuel system correctly? If not you will get a FUEL TANK/ENG message on your EICAS and that would explain why outboard engines are running out of fuel. The FUEL TANK/ENG message is to notify you that you need to configure the tanks such that each tank is fuelling an engine (TANK per ENG, or TANK/ENG).
On the FUEL page, you will see that the only pumps running all four engines up are the OVRD pumps in MAIN 2 and MAIN 3. These pumps are heaving fuel out of these tanks to keep all four engines running, and the reason you’re running all of the engines off of these tanks is that they can hold a lot more fuel than the outboards.
Once the inboard and outboard tanks are all at the same level, though, there’s no longer a reason to be heaving fuel out of the tanks, so you turn the OVRD pumps off, and then set the engines up in a way that they all draw from their own tank (this also ensures that if there’s a leak in a line between one of the tanks and an engine, you’re not going to affect more than one engine.
FUEL TANK/ENG should happen when all tanks get down to being even.
If the FUEL TANK/ENG message pop up, you will need to close the FUEL CROSSFEED VALVE switches and all OVERRIDE FUEL PUMP switches to remove the caution.
Hope this helps.