Fuel pump controller failures:
Sorry to butt in, but:
Anyone who has ever looked at one of the said fuel pump controllers will note that they are "Potted". That is, they are assembled, & then filled with a 2 part epoxy type electicrally insulating, totally waterproof substance.
As a consequence, they will not suffer any damage if submersed indefinitely in water.
BMW now have about 20 different part numbers for these devices. To us poor mortals, these part numbers are for different models of bikes, or superscessions. Actually, all fuel pump controllers are electrically identical and interchangeable.
The part number is two things:
1 A supplier identification number.
2 A superscession number.
The Fuel pump controller is just a PWM device.
That is: Pulse Width Modulation.
The ECU sends a pulse train of varying widths to the Fuel pump Controller,
which interprets it & changes the Fuel Pump Speed via a built in transistor.
I surmise that:
BMW probably did all their testing at relatively high engine loads,where the pump is at full speed, and the transistor is fully on, & thus shedding very little heat.
Unfortunately, in the real world, we do not go everywhere on full power, so the pump is told to run slower. As a consequence, the transistor is shedding much larger quantities of heat.
In the long term, this excessive heat degrades the electronics & destroys the units.
If one compare early & later units, you will see the aluminium heat sink on top has got progressively bigger, & is now black.
Bearing in mind that the failures are probably heat and time related, any replacement redesigns have had to to go through a similar cycle to see if they are better than the original units.
What can one do to extend the life of the unit:
NOTHING.
Either carry a spare, or get it replaced, in the hope that the problem is now "cured"
Since BMW are now replacing the Fuel Pump Controllers one can take it that they have sufficient confidence in the current model that they believe the problems have been resolved (Long Term)
Myke