Member Since: 02 Sep 2014
Location: London
Posts: 42
Is my fuel pump failing?
Background:
Landy (MY07 D3) keeps going into limp mode and dashboard lights up like a Christmas tree.
Turn off and back on, and everything is fine for a random length of time.
Brake switch & lights replaced (lights several times!)
IID shows different faults each time it happens.
In 2C temperatures with 1/2 a tank of diesel and a brand new fuel filter I had the following results:
Current: Starts at 3.8A and rises to 4.2A
Pressure: Starts at 3.5psi and rises to just below 4 psi
Does this indicate that the fuel pump is on it's way out, or is there somewhere else I should check?
The guide mentions the relay could be at fault. Can anyone suggest how to test this?
Last edited by kseventy on 26th Jan 2021 6:06 pm. Edited 1 time in total
23rd Jan 2021 5:58 pm
aja4x4
Member Since: 14 Apr 2019
Location: Westbury
Posts: 2463
Yes pressure is too low, it wont hurt to change the relay but i dont think it will make any difference.
23rd Jan 2021 6:18 pm
kseventy
Member Since: 02 Sep 2014
Location: London
Posts: 42
That's what I thought
Better search for a post on how to change the pump!
23rd Jan 2021 6:45 pm
wedgev8
Member Since: 17 May 2019
Location: Kerpen
Posts: 181
A little more pressure could be better.
But without reading the fault code with a good diagnostic tool I would not change the low pressure fuel pump.
Please read the code and post it.
Last edited by wedgev8 on 26th Jan 2021 6:35 am. Edited 1 time in total
23rd Jan 2021 9:19 pm
kseventy
Member Since: 02 Sep 2014
Location: London
Posts: 42
The codes change every time it happens - there is no consistency.
The only one that repeats is a BCM error to do with the stepper motor on one of the seats, but that reappears just by turning on the ignition!
23rd Jan 2021 9:59 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5044
Post the codes anyway, there is likely some pointers in there! Keep a record before you delete until the issue is resolved. (screen shot) yµ (idµ - eAµ) ψ=mψ
23rd Jan 2021 10:03 pm
wedgev8
Member Since: 17 May 2019
Location: Kerpen
Posts: 181
Yes, the fault code can help.
If you find a code regarding the fuel pressure is too high or low or erratic, this is often a reason for the x-mas tree on the dashboard. Limp mode, Suspension lowered and gearbox fault.
When the x-mas tree comes up, you will find many fault codes with your tool. Mostly there is one code showing to fuel pressure. This is the main fault. The others are followers.
Some weeks ago I had P088..... (Cannot remember) Fuel pressure too high or stays high. This came up every two or three days driving in cold wet weather. Then I cleaned all important connectors with a special contact cleaner spray.
The connector at the fuel rail pressure sensor, all three big connectors on the ECU and very important the earth point where the 4 black wires of the ECU are clamped. You will find this earth point behind/under the wheel arch in passenger side. Open the nut, brush all cable shoes and the bolt, use copper grease and toothed washers and fasten it again.
After this procedure my problem is gone and No limp mode since 4 weeks.
23rd Jan 2021 11:26 pm
kseventy
Member Since: 02 Sep 2014
Location: London
Posts: 42
Thanks for all the input.
Latest codes are as follows:
Auxilary Heater
B1D29-93 (2E) No start, even after restart attempt - Component failure - no operation
U1A44-6C (2E) Fuel level
Body Control
B1B70-81 (28) Local interconnection network bus circuit 2 - Bus signal/message failure - invalid
serial data received
( on 17-11-2020 20:45:20 at 127993 mi )
B1B91-3A (6C) Seat tilt motor speed/position sensor - Frequency modulation/pulse width
modulation failure - incorrect, has too many pulses
( on 07-11-2020 19:16:56 at 127912 mi )
B1C92-14 (6C) Fuel filler door lock relay output circuit - General electrical failure - circuit short to
ground or open
( on 07-11-2020 19:19:50 at 127912 mi )
B1C94-14 (6C) Fuel filler door unlock relay output circuit - General electrical failure - circuit short
to ground or open
( on 07-11-2020 19:19:51 at 127912 mi )
Engine TDV6
P0087-00 (68) Fuel rail/system pressure - too low
Parking Brake
U0100-87 (A8) Lost communication with engine control module/powertrain control module 'A' -
Bus signal/message failure - missing a message
( on 12-11-2020 11:26:13 at 127962 mi )
Ventilation
B1B74-00 (28) Front foot-defrost mode stepper actuator
( on 19-11-2020 19:55:37 at 128006 mi )
B1B75-00 (6C) Front foot-face mode stepper actuator
( on 19-11-2020 19:55:37 at 128006 mi )
B1B76-00 (28) Front left air blend stepper actuator
( on 19-11-2020 19:55:37 at 128006 mi )
B1B77-00 (28) Front right air blend stepper actuator
( on 19-11-2020 19:55:37 at 128006 mi )
25th Jan 2021 10:14 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5044
So P0087 is the one you need to get after, the rest are irrelevant for now. It could be the in tank lift pump is starting to fail, or the fuel filter is blocked. At worst, it could also mean a new HPFP
You could start by replacing the fuel filter with a Mahle or an original LR and see if the pressure recovers. If not, given the readings you posted above I'd be investigating the lift pump before firing the parts cannon for a HPFP!yµ (idµ - eAµ) ψ=mψ
25th Jan 2021 11:45 pm
wedgev8
Member Since: 17 May 2019
Location: Kerpen
Posts: 181
How often do you have the christmastree? Every day?
Warm Up the engine and pull the fuse of the low presure Pump. You will see the car running further.
The HPFP has a pre pump in itself and sucks the fuel from the Tank. So the engine can run from -0.3 bar to +0.5 bar See Workshop Manual. I would suggest Check all earth Points in the wheel arch.
26th Jan 2021 6:59 am
jetmech
Member Since: 22 Feb 2016
Location: Suffolk
Posts: 271
I think that’s going to end up being the hpfp. I spent a lot of time testing and changing the electric pump, never could get the values quoted on here. But have had no issues since changing the hpfp.Simon.
2008MY Dicovery 3 TDV6 SE Manual
26th Jan 2021 9:31 am
kseventy
Member Since: 02 Sep 2014
Location: London
Posts: 42
PROFSR G wrote:
So P0087 is the one you need to get after, the rest are irrelevant for now. It could be the in tank lift pump is starting to fail, or the fuel filter is blocked. At worst, it could also mean a new HPFP
You could start by replacing the fuel filter with a Mahle or an original LR and see if the pressure recovers. If not, given the readings you posted above I'd be investigating the lift pump before firing the parts cannon for a HPFP!
These settings were taken using a brand new Mahle filter - 0 miles!
26th Jan 2021 6:00 pm
kseventy
Member Since: 02 Sep 2014
Location: London
Posts: 42
wedgev8 wrote:
How often do you have the christmastree? Every day?
Warm Up the engine and pull the fuse of the low presure Pump. You will see the car running further.
The HPFP has a pre pump in itself and sucks the fuel from the Tank. So the engine can run from -0.3 bar to +0.5 bar See Workshop Manual. I would suggest Check all earth Points in the wheel arch.
It used to be only when SWMBO was a passenger , but now it happens nearly every journey.
Last 2 journey's it seemed to coincide with the engine hitting operating temperature, but I haven't noticed that before.
26th Jan 2021 6:03 pm
kseventy
Member Since: 02 Sep 2014
Location: London
Posts: 42
jetmech wrote:
I think that’s going to end up being the hpfp. I spent a lot of time testing and changing the electric pump, never could get the values quoted on here. But have had no issues since changing the hpfp.
I hope not, but will set the IID to record the live values when I next go on a journey to see if they show any pressure drops/fluctuations
26th Jan 2021 6:05 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5044
Well at least thats the filter ruled out, but I still think your lpfp output is just that bit too low.
When you had the pump out what was the gauze like? They are very prone to sludge/algae build up!
Also, you need to be certain all it's elecs are sound particularly the earth as suggested above, and running the diagnostics will show the rail pressure dropping leading to P0087.yµ (idµ - eAµ) ψ=mψ
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, but now it happens nearly every journey.
