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Hi all,

Wonder if anyone can help with a few points.....

I was driving the other week on dual carriageway and on overtaking a car dash flashed up "Fuel Injection System" then completely shut down.....anyway managed to pull over and car restarted after ignition off to re-set, since then have driven very steadily and all ok.....


Anyway, I have INPA so hooked it up and got codes in three sections at same mileage, 4560 (3002) plausibility rail-pressure volume regulated, 4570 plausibility rail-pressure volume regulated, 4610 plausibility rail-pressure volume regulated.
"
Now I assume that on the readout for example on fault 4610, "maximal rail pressure of the last 10ms 661.68 bar" and "rail pressure index value 1150.06 bar".....the 661.68 bar is what has been recorded, and the 1150.06 bar is where it should have been. Would that be a correct assumption, that was my first query?


I then changed the fuel filter (not relying on this to be the fix) and thought that I would run the INPA live (whilst parked) to see if I could see a discrepancy in the desired/current or nominal/actual fuel rail pressures at different RPM's.....


The bit I do not understand are the live readings, although nominal and actual stayed relative to one and other, seemed way too low to me from my understanding....approximately 700 RPM = 316 bar, approximately 1600 RPM = 402 bar, approximately 3000 RPM = 550 bar and approximately 4000 RPM = 650 bar....am I missing something here? If too low, why are readings agreeing with each other?


Although the above was under tab F6 (desired/current), I cannot seem to get to readout screens that others seem to get like the low pressure fuel pump (fuel pressure readout etc)?


If anyone could offer clarity or help to any of the above, or pointers to actual fault, (linking all fault codes together) I would really be so thankful...:confused:confused:confused
 

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You got it right on the first one. Actual fuel rail pressure was way below the demand and that caused the shut down.

On the second one the demand for rail pressure is that low because there is no strain / no actual torque needed when revving stationary.

The problem with these (like the late E46 330d with M57N engine) is that they have the old style separate in-tank fuel pump and inline fuel pump but no monitoring for fuel supply pressure. So a supply pressure problem can also cause a low rail pressure problem. How much fuel was in tank when this occured? If above ~1/3 that should rule out in-tank fuel pump. That still leaves a possible problem with inline fuel pump and one typical problem is starvation on high load. If the supply is OK before HP fuel pump there are several possible problems on rail pressure side. Some typical being a leaky injector (measure injector leak off, in most cases also causes slow starting), failed fuel volume regulator (at the rear of HP pump), failed pressure sensor (should cause problems in other situations too) or failed HP fuel pump (fairly unlikely).
 

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Discussion Starter #3
You got it right on the first one. Actual fuel rail pressure was way below the demand and that caused the shut down.

On the second one the demand for rail pressure is that low because there is no strain / no actual torque needed when revving stationary.

The problem with these (like the late E46 330d with M57N engine) is that they have the old style separate in-tank fuel pump and inline fuel pump but no monitoring for fuel supply pressure. So a supply pressure problem can also cause a low rail pressure problem. How much fuel was in tank when this occured? If above ~1/3 that should rule out in-tank fuel pump. That still leaves a possible problem with inline fuel pump and one typical problem is starvation on high load. If the supply is OK before HP fuel pump there are several possible problems on rail pressure side. Some typical being a leaky injector (measure injector leak off, in most cases also causes slow starting), failed fuel volume regulator (at the rear of HP pump), failed pressure sensor (should cause problems in other situations too) or failed HP fuel pump (fairly unlikely).
Thanks for your help Clavurion, I did think to myself that it could be showing low rail pressure because of no load as it were so glad to have it confirmed....

The fuel level in tank was pretty much full. So INPA is not capable of displaying the low fuel pressure on my model then, I thought it was me not knowing my way round the software!

Well I guess I will give the car a real test to see if the fuel filter seems to have done the trick or not, its just so bad for the cut out to happen when it typically does (normally overtaking)….

If fault still present then maybe best way forward would be to look at replacing inline fuel pump and also leak off test.....

Many thanks
 

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Discussion Starter #5
That sounds like a reasonable plan.
Thanks Clavurion…..

Just one thing, is the inline fuel pump after the fuel filter or before......I was just trying to figure whether the fuel pump is included in the 4 bar pressure or so to the high pressure pump or not!


Thanks !!!
 

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Before the filter. Not sure where it is exactly on the E53 (my 2004 E53 is fairly new to me), but on my 2000 E46 it's underneath the car behind a heat shield under the passenger seat area so would guess it may be similar on the E53. When you switch the ignition on you should be able to hear it humming for about 20 seconds which might help you track it down (or not if it's dead of course!).

If the inline pump is on the way out, it is sometimes caused by the relay for it giving up rather than the pump itself. It uses a kiwi coloured relay which is the same as that used for the horn and indicators so you can swap them over to rule the relay out before you go in heavy on the pump. From recollection I think there are a load of relays in the off side rear boot compartment so I'd start there (the manual also tells you which ones are which).
 

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And yes, feed to the HP pump should be about 4 bar from recollection - that being enabled by the inline pump. Generally, if the inline pump gives out (or the relay) it won't start - if it gives out whilst driving usually it won't rev but still runs until you stop it, after which it won't start again.

Changing the fuel filter is a good move - dirty/clogged can cause some weird symptoms, including random conking out!
 

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Discussion Starter #8
Thanks Evog, the inline pump is near the fuel filter in front of the fuel tank....you gain access from under the vehicle....

I was not too sure in which order the fuel filter and inline pump were connected, I was thinking that the 4'ish bar pressure was not included in the fuel filter but thanks for correcting me.....it was more about the tightness of the clamps on the fuel filter connections and that I did not want to overtighten them at the time thinking only low pressure, now I am thinking whether I tightened them enough, hope so !!!


Thanks again....
 

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Hi all,


UPDATE

Well since diesel fuel filter change, X5 is running well and has not had a repeat of the original fault of cutting out on acceleration due to low fuel rail pressure.

I did only just get around to cutting the old filter open and was in a poor way, the element was covered in a slimy or sticky oil type substance which I am certain would have restricted the diesel flow quite severely. On research it seems it could well have been asphaltenes, don't know if this sounds familiar to anyone (would be interested to hear), but anyway I was sort of pleased as has given me somewhat confidence that this was the issue.....


I thought I would share anyway as to potentially aid others!
 
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