N47, fuel pump problem? Cutout

[bearman68]

Hi Folks.

So here's my little method for checking the intergrity of the HP fuel system. This is pretty much my first check on any troublesome common rail engine.

1) Find the HP fuel rail pressure sensor.
2) Middle wire should be 0.5v ignition on, engine not cranking.
3) With the engine cranking, this reading should take maybe less than a second to come up to about 1.1v (some variation is possible, and the multimeter will have delays).
4) Stall the engine (5th gear, and drop the clutch stall). The 1.1v should take about 5 seconds to gradually reduce to 0.5v.

So what does this tell you??
1) If the ignition on engine off voltage is not 0.5v, the sensor or the wiring (or the ECU) is in trouble.
2) If the voltage is slow to come to 1.1v (>2 seconds), it tells you either there is a shortage of HP fule, or there is a mechanical leak in the HP system.
3) If the voltage quickly drops to 0.5v (<1 second), there is definitely a leak in the HP system, and it needs to be found.

This is the graphical view of it. https://www.picoauto.com/library/automotive-guided...

[bearman68]

bmwrider said:

A few weeks ago while driving (530D E60, 2009) I recently suffered from a sudden loss of power,

Now I did the test you have suggested for the previous guy, my readings:

At stationary:
cable left: 5v
cable middle: 0.5
cable right: 0.01v

---

With the engine running:
cable left: 4.97v
cables middle: 1.26 ~ 1.31v
cable right: 0.01

Any more tips as to what to check?

Yes, stall the engine while keeping an eye on that fuel pressure. It should take >5 seconds to fall to 0.5v. If it does, there's nothing mechanically wrong with the HP pump or the injectors. (Doesn't rule out electrical issues with the injectors mind)

[bearman68]

And lastly, these tests are good for pretty much any common rail engine, 4 cylinder, 6 cylinder, all use the same values for fuel pressure control. (Some Fords use 1.0v base voltage not 0.5v, but let's not worry about that here).

[Dindiesel]

Hi all,
Long time reader/first time poster....
I've a problem;
Bmw 2009, n47, 520d, 260k Miles.
It's throwing 2 codes 4BDC and 4BDA.
To date I have used quality diesel and Mann diesel filters every 25k miles.
So;
Injectors pulled, checked by a guru and 2 swapped out and coded in although they were functioning.
Fuel valve on hpfp replaced for brand new bosch one, no metal fillings present.
In-tank lpfp replaced for brand new bosch one.
Fuel module in trunk/boot swapped for second hand one, no change, fault still present.
Tank filler cap replaced for brand new one.
No evidence of any Fuel leaks at all. All covers removed and pipes scrutinised.
Back probed temp/pressure sensor under hpfp, 4 wire sensor. Ground and signal noted. One signal wire was 3.5v dropped to 2.5 engine running?
Unplugged said sensor and low pressure problem still present when driving but code not coming up(4bdc), no additional code, only that signal lost to sensor.
Fuel rail sensor (front) back probed, signal and ground. I think it dropped to 0.7 volts on engine running but i expected as low pressure. Looked for leaks. Considered return line on injectors damp so redid seals. Going to swap out pressure sensor for second hand one for cross check.
Rear pressure valve on rail not checked yet, to do.
Fuel filter is warm so heater assumed working.
Car starts easy, even in frosty weather.
Car drives well but has low top end power possible due to high reading from dpf due to inability to regen due to fuel pressure issue.
No hiss of air when fuel cap opened on a low tank.
Possibly drives better before car/fuel heats up, not sure.
At low speeds, revs fluctuating and an elastic band driving sensation.
High speed is fine.
My next step is to change the pressure/temp sensor for a second hand one, €40.
I've exhausted YouTube and Google for answers.
Any help would be greatly appreciated.
Thanks
Den