This is better than a "black box". :thumbup:

BMW M57TU fuel flow...
https://i.ibb.co/JsQTLYg/M57-TU-Fuel-Block.jpg

Cick the image for a larger version.

And yes, you read that correctly - the HPFP output is up to 1600bar (23,206psi).

Don't screw with diesel fuel rails when they are running!!! :yikes:

The diagram shows the excess from the supply fuel pump doesn't go to the filter/FPR before going to the siphon jet that doesn't seem correct.

Also what is the B line to the injectors for?

The diagram is for the M57TU engine in general and may not be E53 specific in relation to the actual tank arrangement... :dunno:

The B line from the injector is the injector leak-back line. In the image below, dark purple is HP fuel to the injector and light purple is LP fuel from the injector leak-back.

https://s19529.pcdn.co/wp-content/up...jector-45.jpeg

I have had 2 no start situations in the last month. The first I was in a hurry and figured I had not allowed enough time for the glow plugs to heat up. It started second try.... The other no start situation was just a week ago, it wouldn't start after 2 attempts, I pulled they key out of the ignition, put it back in and it started fine. As it was still a somewhat isolated incident and was showing no other symptoms of anything being wrong, I thought nothing of it.

Fuel Injection System Error
 

If you had reported those two situations without other new ones the #1,2 and 3 most likely candidate of failure would be the ignition switch.

It's nearly 100 chance of what caused the problem for the exact thing you did; tried a couple times and after I took out the key and tried again it started. That's the exact symptom of a failing ignition switch

That would be a lot easier and cheaper fix than anything fuel related on a diesel.

If you can get 2nd level codes read it will be very helpful. If say you hit a bump it jiggles the ignition switch and kills power momentarily when driving you will usually see the low voltage error on a lot of systems.


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Hmmm, Its definitely worth exploring then. If it were a failing ignition switch, would i generally lose accessories with the moving stall? All power accessories (radio, fans, instruments) were completely unaffected aside from the quick "fuel inject system" warning that flashed on the display.

The idea is momentary blip of power loss. Example: when a cam shaft sensor stops sending the signal the engine computer has no alternative than to cut power to the injectors. It literally doesn't know where the camshaft is within the cycle so can't determine when the fuel should spray or the spark should fire.

If any mission critical component is affected the engine will.shut off to save the engine from self destruct. If the power blip is short enough you won't even notice. The accessories will still run.

Consider: if you turn the key one click back the accessories still run but the engine shuts off and if you turn back to start position nothing happens. Eg engine will not start running again. I don't think it matters if you do it fast enough that momentum carries the engine far enough it would run the computer won't send fuel or spark.

You are right, I guess if the switch is faulty in the "ignition" position, you could still crank it over while the car essentially thinks its just on "accessories" too. A bit of research shows the switch to be a reasonable common issue with similar (albeit not quite identical) symptoms. They are cheap enough to take a gamble on so I might just order one and throw it in while I wait on my friend with his software etc.