Rather than fuel pumps failing I think I would initially looking at where the air is getting into the fuel system.
Why would any pump failure let air into the system?

ok thanks, so if the in tank is only transferring one side to another, and had or failed i assume if you were at half tank capacity, it would not start again until you filled up? is that correct thinking? i dont recall what the gauge said on the first time is stopped, but i had started with a full tank and had driven about 300 K so would not have been at half tank, also on way back when it started stopping again several times, i was im sure above half tank, but wou ld it give the symptoms i have if it was a failing tank pump?

i wonder if it would be worth the gamble to get the garage to change it just as a process of elimination??

its all very awkward as im not at the garage as it is up country a few hundred km away

No more fuel in RH side of tank means secondary pump sucks air in stead. First a mix of fuel and air. Look at the second page from RAVE that mjdronfield posted, this clearly shows the tank construction. The in-tank pump wich is in the bottom of the combined pump, fuel pick up, and fuel gauge unit shown in the second to last page from mjdronfield.

Key question, have the problem ever occured with 3/4 or more fuel in tank ? I ran empty with 48 liters left in the tank (you can read what is in each tank half on the hidden service menu on the instrument cluster display)

BOBCUSSEN wrote:

ok thanks, so if the in tank is only transferring one side to another, and had or failed i assume if you were at half tank capacity, it would not start again until you filled up? is that correct thinking? i dont recall what the gauge said on the first time is stopped, but i had started with a full tank and had driven about 300 K so would not have been at half tank, also on way back when it started stopping again several times, i was im sure above half tank, but wou ld it give the symptoms i have if it was a failing tank pump?

i wonder if it would be worth the gamble to get the garage to change it just as a process of elimination??

its all very awkward as im not at the garage as it is up country a few hundred km away

^ Does that mean if you fill the fuel tank the car will drive normally with no air in fuel?

no all im saying regarding the symptoms is when the engine was left running in the first no dealer garage, they had changed the filter and let it idle for 2 hours, and all was fine then bubbles appeared in the line by the filter and they started small then got bigger and the the engine stopped, so this is i assume what happens every time it cuts out ;

i dont know if filling the tank will stop the problem; all i know is i had a full tank at the start and after 300K the cutting out started, but on the way back, i was about three quarter full but still after about 100k it started again, then it cut out 6 times more at an interval od about 8/10 k

,,,,,,???

at this point the second garage had being a dealer said it was not the main but the secodary ump and changed that but it still has not solve the problem

bob

hi guys;

i think it may prove benificial to tell you the usage of this car, as it might have some bearing on what is the possible / probable cause of this problem, other than pumps etc;

the car is a uk spec right hand drive which i bought in 2012. it get used very little, perhaps once a week and generally no more than 100 KM.

in that period the car has been driven back to the uk 3 times only and apart from perhaps another 2 times, it would never have more than half tank on diesel and most of the year i would expect the tank to be at no more than a quarter full !! so i have done no more than 20.000 MILES since 2012

so i wonder if that points to anything now more likely to be the cause ??

so how does the in tank pump actually work ? does it wait for one side to empty then transfer all from one side to another? or does is it working bit by bit, ? what im getting at is if i am not generally filling the car up, then then is that going to make the pump work more or work less ? ie is it better to keep the car full and re top up when it drops to say 3/4, or better to keep it low, ie under half , due to the little usage it gets.

so another way to ask is this, i normally wait until the 100km warning chimes, then i add some fuel to the tank, so would the pump be basically sitting idle most of the time or working its arse off ???

as you know already, the secondary pump has been replaced by the dealer, and im still trying to get them to tell me why they changed is and what the fault code was but they wont say, so i think it was just changed as a possible reason for the fault;

th car is today being trailered to a dealership which is about 250KM from me and they will look at it next week, so i have time to contact them and suggest what i would like them to do/change, or not to change, as the case may be, ie the main pump;

nicedayforit made a comment about why would a pump failure cause air bubble in the filter line, ( which is what happens, then a lot of cranking to get the fuel up again, !!! that does sound like a possible in tank pump problem or relay do you think;??? now that it has been said it would pull air up ?

the car is drivable, so i could bring it back but at the time i didnt want to risk going on single roads in rush hour etc;

im thinking to let them do a check, and see what they come up with, and if nothing then just to tell them to renew the relay and change the fuel tank pump, and then see how i get on; any thoughts please im very grateful for all your input

If you open the rear fuse compartment the relays are labelled on the list in the fuse box. I think it's the 4th one from the left. The rear seat heater relay is the same type, easiest test is to swap them. No need to buy one, it's a 30 seconds job from unlocking the car!

If there's air in the fuel, I wonder if there's a leak on the in-tank fuel transfer pipe? Or a plastic connector somewhere is cracked and opens up when hot? I don't know the diesel fuelling after the tank.

Hmm, infrequent use and perhaps some bad diesel that could cause screen in in-tank sender/pump unit to be clogged. Would also clogg fuelfilter quickly. There are additives to kill bacteria in diesel to stopp such growth, also good idea to have full tank when in storage for long time.

Each side of the fuel tank has a gauge, the sum of these is what is displayed in the instrument panel. The pump is triggered to run when there is more fuel in the LH than in the RH, means it doesn't run all the time. The fuel level reading in each tank side can be seen in a hidden servcie menu. As mentioned I ran out of fuel with 48 litetrs left since most was in the left hand side of the tank.

Since the bubbles in the clear fuel pipe comes when hot i wonder if it could have to do with the fuel cooler.

What is the total milage of the car ?

It is more than likely to be the in-tank fuel pump that has started to fail. I had the exact same problem just before Christmas, driving along then engine dies with Fuel Inject System error on dash display. Restarted car after a minute and all fine for a short while, then same thing. Kept doing this at random, and I had 1/2 tank of fuel in the car. It was the in-tank pump not working properly, as it is supposed to operate all the time and supplies fuel to a swirl pot from where the secondary pump can take its feed from. The in-tank pump also transfers fuel from side to side within the tank through a siphoning action, but its main function is to feed the secondary pump. If the secondary pump takes in a bit of air because there isn't enough (or any) fuel being supplied to the swirl pot, this air gets passed through to the air filter, which has a pressure sensor on it. If the pressure drops below a set point, the sensor tells the engine ECU, the ECU shuts down the High Pressure Pump to prevent any damage to it and the engine dies.
If you keep the tank brimmed with fuel, you should be able to get the vehicle home, a full tank will keep the fuel level above the swirl pot. You don't need to replace the entire in-tank sender unit (costs about £290 from Island 4x4, BTW) as you can get just the pump itself. I got a genuine BMW Pump off ebay for £36, took out the in-tank unit, dismantled it and replaced the pump, all in all it took me around 2 1/2 hours to do. Solved the problem.

hi guys


thanks again for all the ideas, and it does seem to be leaning toward a possible/probable in tank pump??; it is the first time i have had a problem since owning the car but my only concern is if it is that pump, why has it only started to happen with a full tank or three quarter tank in the way back breakdown ??? as normally there is not much over quarter full for since owning it and never had a problem on carrying low volumes of fuel;

;; anyway i might as well let them don the diagnostic as it has cost so bloody much to get the car to where it is, then see if they come up with any fault codes which i doubt, then ask them to perhaps change the in tank pump? after changing the relay over? or just do the relay test, fill it up and head back home ?

am i right in thinking the relay is for the secondary pump? r is it for the in tank pump or main ??

thanks again and sorry for all the words and questions,

by the way the car has done 130K MILES

SORRY ANOTHER FORGOTTEN QUESTION

how do i get to look in the hidden menu on the screen ?

I thought it was in the wiki, but couldn't see it:


Ignition key must be “off”.
• Press and hold the Check Control button in the instrument cluster (RIGHT button), and turn the ignition key to the first position (KLR).
* You will first see "Check Control OK", some seconds later you will see "Test Nr.01"
* Push the left button on the instrument cluster to see the car's identification number. Add the5 digits (not 6) together and write down that number, you will need it for unlocking all the functions. Example: A123457 will lead to 2+3+4+5+7 = 21
* Push the right button until you see "Test Nr.19"
* Push left button until you see the number that is equal to the one you calculated above
* Push right button again

1. Display Car's identification number, HW/SW version, construction date
2. instrument cluster self test. Will light up all lights and run all guages
3. Current consumption (liters/hour)
4. Average consumption (liters/100 km)
5. Current range
6. Remaining fuel in tank. Three sets of numbers: A/B/C. C=total amount.
7. Engine RPM / Coolant Temp (C)
8. Current Speed (kph)
9. System voltage at Term. "R" (Battery Voltage)
10. Country/Language (UK, US, Spa, Ger, Jap, etc.)
11. Units am/pm
12. Average Speed
13. ETA
14. Date of Software Mask
15. Production Diagnosis
16. ""
17. Display Vehicle Specific Data
18. Alarm Changeover (cont. vs. intermittent OBC chime)
19. Lock/Unlock
20. Correction factor for fuel consumption (nicht ändern!)
21. Reset all defect codes

great thanks for that info; i assume no 6 being the one im after ?, and guess A and B IS left and right levels;

so if for example it was 30L LEFT 15 L RIGHT? would that indicate a possible pump failing?? and i assume a few litres plus or minus would be the norm and acceptable !!

No 6 is the one. 30 Left and 15 right could indicate partial in-tank pump failure but not conclusively. If left stays steady at 30 while RH goes lower while driving for a while then yes. Typically the pump fails internittently so in the beinging it is not that easy to spot. Looked at min yesterday; 38 & 34 so some liters difference is normal either way.

Relay is for both pumps as far as I can read the description in RAVE, the ECU can still operate them separately.

Have been thinking more about the "air in the clear fuel pipe by the filter when eninge gets warm and then stalls" symptom. There is a fuel cooler in the system that is controled by a bimetallic valve. When fuel get over 85 degrees celcsius it gets cooled in the fuel cooler circut. Could it be air gets in when valve is activated.

Have one or more of the diesel injectors on the car been changed or serviced ? with 130 K Miles on the clock I would guess so but if not all has been done it could be a dodgy injector. Since you will have the car hooked up to read fault codes ask them to do a live injector data reading; fuel compensation in mm3 per cylinder. get the readings both cold engine and warm. They can also read the fuel pressure on both lo and high side to see if there is anything wrong with the fuel pumps.