Not sure that I would agree with the fact the low pressure pump is only needed to prime the system when changing filter etc, on my motorhome if you remove the power supply to the low pressure pump while the vehicle is running it stops the engine, if no power to the low pressure pump when starting the vehicle it will just contine to turn over and not start. As far as I understand the system the ecu sends a signal to the low pressure pump every time you turn the ignition on this runs the pump for 10 seconds to prime the high pressure pump from then when the engine runs the cam sensor and high pressure pump comunicate with the ecu and the low pressure pump.
Be interested to know if any of you dissconect your power to the low pressure pump if your vehicle continues to run mine will deffinatley not.
Regards to all