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Low fuel pressure codes caused by limp mode on acceleration?
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PROFSR G
 


Member Since: 06 Mar 2017
Location: Lost
Posts: 5036

Ukraine 2009 Discovery 3 TDV6 Commercial XS Auto Stornoway GreyDiscovery 3

So there's not enough pressure at the rail it seems. Either the HP side is faulty or possibly low pressure side is intermittently faulty or the pipes are incorrectly connected.

Clear the codes then remove the fuse for the LPFP, the car should drive fine with the pump disconnected so long as you are light on the accelerator. If it fails this test have a look at the codes and post them here, but my suspicion is that this is a high pressure side fault.
 yµ (idµ - eAµ) ψ=mψ

 
 
Post #23769459th Sep 2024 6:25 pm
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James M
 


Member Since: 19 Dec 2023
Location: Scotland
Posts: 26

United Kingdom 2005 Discovery 3 TDV6 XS Manual Aintree GreenDiscovery 3

Yeah rail pressure seems to be a constant problem when the car is first started it’s about 28,000 kpa but once it warms up it drops down to 22,000 kpa and is very fluctuating going up and down like it’s surging / struggling to suck fuel.

The low pressure side has had two new intank pumps , new non-return valve/ tank cover , and lots of filters , and all pipes look fine

So is this test supposed to show that if the hpfp is fine then the car should still run ?
What dose it mean if it won’t start or stay running ?

Yeah it dose just keep looking like it’s the hpfp but what are the chances of getting two new pumps that are both faulty, one after another and then just take the gamble that third times a charm ?
  
Post #23769499th Sep 2024 6:52 pm
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James M
 


Member Since: 19 Dec 2023
Location: Scotland
Posts: 26

United Kingdom 2005 Discovery 3 TDV6 XS Manual Aintree GreenDiscovery 3

Ummmm if the fuel pipes just befre before the high pressure fuel pump / feed and return where the wrong way around would the car still run and drive relatively fine but always be struggling for fuel , cause I do remember seeing personally that both metal pipes seem to pump fuel when the ignition is on ?
  
Post #23769549th Sep 2024 7:38 pm
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PROFSR G
 


Member Since: 06 Mar 2017
Location: Lost
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Ukraine 2009 Discovery 3 TDV6 Commercial XS Auto Stornoway GreyDiscovery 3

I might be something small but your mechanic is only going to get to the bottom of it by studying carefully what is happening in "live values" and understanding the data.
The oil temp switch in the sump plays an important role here, so it should be monitored closely to eliminate any erroneous signals or switch failure.

It may be something simple, and especially so if you have replaced the major components / pumps and other bits. Did he do a "reset" for the LPFP when it was fitted? Doing so will request the PCM to reset it's adaptations for the LPFP pump and might improve things. Another area that can cause issues is the electrical plugs on the FRPS/HPFP, or even the diesel EMS fuses in the BJB as sometimes they are tarnished or not making full contact with the pins.

Have a look at the screen shot below and you get some idea of what the live values for the fuel system sensors should be doing at idle speed on a healthy engine. These were taken at an idle speed of around 725 rpm, so a lower rpm will bring down the fuel pressure value to around 23.0 kPa.
It's normal for it to fluctuate slightly, eg 22.5kPa to 23.0 kPa or a bit beyond, but not wildly eg 22.5 kPa to 26.0kPa when idling.


Click image to enlarge


The screenshot shows the fuel pressure at the rail, the HPFP volume & pressure control valves operating values, mass air flow, manifold pressure, battery voltage and turbo boost values all taken at 725rpm.

Throwing parts at the problem hoping you hit the "bulls eye" is never a good idea as I'm sure you know by now. Working through the issue methodically, and understanding the data until you start to see something in diagnostics that doesn't look right is really the only way forward. Sometimes you can get lucky but rarely with these complicated fuel systems.

The LPFP fuse removal test is only useful for confirming the complete system is operating correctly, but with it removed it can sometimes point the direction of the fault depending on the codes presented. If you could provide live data from the engine and post it here it would help working through the problem, if that's an option for you.
 yµ (idµ - eAµ) ψ=mψ

 
 
Post #237701710th Sep 2024 1:38 pm
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James M
 


Member Since: 19 Dec 2023
Location: Scotland
Posts: 26

United Kingdom 2005 Discovery 3 TDV6 XS Manual Aintree GreenDiscovery 3

Hi thanks so much for your help so far !

Well I do have quite a few different graphs / live values that I have taken over the years this it’s had this fault


Click image to enlarge


This is was taken just siting idling

Click image to enlarge


This is a 0-60 graph you could call it but of course the car doesn’t make it to 60 with out going ping
It also shows all the pressures and values positions just before the car gives up and gos in limp mode


Yeah the oil temperature sensor was replaced a few years ago cause it was giving fault codes but seems to be fine now but I can get then to double check

Yeah the lift pump reset has been done a few times

They have tested the wiring back to the fuel box so I’d guess he’s looked at the fuse / had to take it out to test the circuit

Oh I know they just keep throwing money / parts at it to basically save time I’d say and then when you try and say why did you get it wrong again it’s all “ process of elimination “ and trying to find what the fault isn't at this stage , lucky there is currently an abandoned D3 in there car park that they are now taking bits of to try on mine just to “ eliminate “ stuff
  
Post #237704010th Sep 2024 5:17 pm
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PROFSR G
 


Member Since: 06 Mar 2017
Location: Lost
Posts: 5036

Ukraine 2009 Discovery 3 TDV6 Commercial XS Auto Stornoway GreyDiscovery 3

From the graph you provided it's clear that the high pressure rises steadily until you hit around 140kPa, and judging by the other values it seems you were giving her a good hiding too! Laughing

These are from an EU4 engine but they have identical operating parameters.

This first one shows some live values on a relatively cold engine.
Click image to enlarge


This one shows the differences at full operating temperature.
Click image to enlarge


Comparing these with your own above there is nothing that jumps out, but it would be a good idea to watch your battery output alongside the fuel values. Forget about torque as it's not relevant for this diagnosis, just focus on the fuel pump data, battery, oil temp, etc. Thumbs Up
 yµ (idµ - eAµ) ψ=mψ

 
 
Post #237706210th Sep 2024 7:35 pm
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James M
 


Member Since: 19 Dec 2023
Location: Scotland
Posts: 26

United Kingdom 2005 Discovery 3 TDV6 XS Manual Aintree GreenDiscovery 3

Hey , thanks for your thoughts

Hahah yeah when you hit her that hard you’ll only get about 3-4 seconds before ping
But sometimes if you drive very carefully you could do hundred miles with out fault next day you’ll only get ten miles before ping for no reason realy

Yeah I see what you mean I was a bit focused on that it had to be 27,000-28,000 kpa to be normal but like you say at idle as long as it’s above 20,000 then it’s still fine guess it’s all about how quickly it can pick up the pressure when you need it.

Oh well I guess that’s good in a way there definitely nothing obvious sticking out that the dealer should of noticed quickly , strange how everything looks fine but at the same time the fault is there the hole time.

Thanks again for your help Bow down I will definitely pass your advice over to my master technician tomorrow
And I’ll defo keep you posted if we make any progress, or the cure if there is one Big Cry
  
Post #237707510th Sep 2024 8:44 pm
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Farmer Chalk
 


Member Since: 06 Mar 2013
Location: Independent Republic of Kentishshire.
Posts: 4195

England 2008 Discovery 3 TDV6 HSE Auto Tangiers OrangeDiscovery 3

Had a very very similar issue to yourself and reported on another similar threads..

Mine has appeared to have been cured by a replacement genuine JLR fuel rail with the new fuel rail pressure sensor attached… I say appeared purely as I’ve only had it back a couple of weeks but even so I haven’t been able to provoke the car into limp home mode since…
  
Post #237707910th Sep 2024 9:15 pm
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PROFSR G
 


Member Since: 06 Mar 2017
Location: Lost
Posts: 5036

Ukraine 2009 Discovery 3 TDV6 Commercial XS Auto Stornoway GreyDiscovery 3

The FRPS might well be an issue here as it's not available separately from LR without buying the complete rail. So it seems only aftermarket sensors are available and I'm not a fan of them. I have tested aftermarket rail sensors on a perfectly working D3's just to see what the result would be. They worked, and there were no faults but the power was down considerably.

When I replaced the old LR sensor and power was restored, so as Farmer Chalk suggests this is worth perusing further especially as the fault code you are being presented with now is P0087!!

This applies to aftermarket HPF pumps as well, but unfortunately it seems new original Siemens/VDO pumps are no longer available for the D3. Only reman, but I'm happy to be corrected and even happier if someone has a source of new pumps.
 yµ (idµ - eAµ) ψ=mψ

 
 
Post #237709110th Sep 2024 11:31 pm
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James M
 


Member Since: 19 Dec 2023
Location: Scotland
Posts: 26

United Kingdom 2005 Discovery 3 TDV6 XS Manual Aintree GreenDiscovery 3

Hey
so thing just get better and then worse at the same time Big Cry
So spoke to the workshop manager today so on Tuesday they changed the fuel rail pressure sensor after taking one of another persons car just to make sure , then when out for a test drive and it drove great apparently he was doing over 85 mph up a long stretch of hill motorway normally when they take it on the motorway they can’t get from the 50 zone up to the 70 zone without it pinging.

So he then took it out again Wednesday and when he was flooring it up the slip road it just cut out on him and he couldn’t get it to restart , it has never ever cut out like that before to me or them , so they had to get it recovered back on a brake down.

They are hoping that the fault has finally failed / showing it’s face stoping the car from running now and it should be easy for them on Monday to find what’s been wrong it the hole time
But all I keep thinking it that something else has now failed and the engine could be dead , like timing belt or cam chains has snapped , or something stupid they ran out of fuel

Hoping it’s good news in a way but also preparing for the worst !

Thanks for your advice about the pressure sensor it was already changed once for a cheap one but made no difference so put the old one back in , but looks like the dealer wanted to try again.
  
Post #237719812th Sep 2024 11:01 am
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James M
 


Member Since: 19 Dec 2023
Location: Scotland
Posts: 26

United Kingdom 2005 Discovery 3 TDV6 XS Manual Aintree GreenDiscovery 3

So they have worked on the car Wednesday and Thursday but still can’t get it to restart they tho putting the old fuel sensor back in should get it back running again but it didn’t

They are now saying that it’s pretty obvious now that the new high pressure fuel pump that they installed last year has now completely failed and looks to have been the fault all along and they have now ordered another brand new pump and are going to drop the fuel tank again to clean and flush all the fuel lines just in case there it dirt that is killing all theses pumps , and they said it’ll all going to be covered under the Land Rover warranty form the pump since it’s under two year old , like 3 grands worth of work again

But yeah it’s almost hard to believe that the first high pressure fuel pump we installed after the car stoped running years ago was faulty from day one then last year the dealer replaced it with another brand new pump and then that one only lasted 30 miles before throwing up low pressure fault codes again not even getting us home with it before having to take it straight back to the dealer then leading to a hole year of changing and chasing other parts with no one wanting to believe two faulty pumps in a row , so if it hadn’t failed now then who knows when it would of been blamed !

So I should know by the end of next week if they get it back running again and keeping everything crossed that it’s finally fixed !
  
Post #237780920th Sep 2024 7:32 pm
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James M
 


Member Since: 19 Dec 2023
Location: Scotland
Posts: 26

United Kingdom 2005 Discovery 3 TDV6 XS Manual Aintree GreenDiscovery 3

Now I must admit that my 2005 green D3 has never been any trouble in fact all this issue has been from my second car are 2007 Range Rover sport 2.7tdv6 , but I wasn't getting much help from the RRSPORT forum unlike the D3 forums!




Click image to enlarge
  
Post #237781120th Sep 2024 7:51 pm
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James M
 


Member Since: 19 Dec 2023
Location: Scotland
Posts: 26

United Kingdom 2005 Discovery 3 TDV6 XS Manual Aintree GreenDiscovery 3

Well this sport is just unbelievable / is this dealer completely incompetent!
so to replace the high pressure fuel pump again they decided to remove the body for better access and to also inspect the fuel line and clean then out along with clean the tank just in case there is dirt.
They spent a few days doing all this then after putting the body back on they got the car to restart with ease first test drive was driving fine then the next day the technician took it out again then the next day the workshop control manager and a driver took it out and on a long straight they got up to 85mph and it went in to restricted performance and completely lost all power and practically crawled to a lay bay where they stoped and started it again and then it drove back to the dealer fine.
Now they are completely stump and haven’t got a clue what it could be and it sound like they are ready to give up , apparently there has been very few cars they haven’t been able to fix but this must be one of the worst ones there saying.

There has been so much time and money in this car that ill never get back if I just park up and to rot or worse scrap it what else is it good for if it just keeps randomly going in restricted performance.
  
Post #238003722nd Oct 2024 9:47 am
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PROFSR G
 


Member Since: 06 Mar 2017
Location: Lost
Posts: 5036

Ukraine 2009 Discovery 3 TDV6 Commercial XS Auto Stornoway GreyDiscovery 3

Where in Scotland are you?
 yµ (idµ - eAµ) ψ=mψ

 
 
Post #238004222nd Oct 2024 11:54 am
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James M
 


Member Since: 19 Dec 2023
Location: Scotland
Posts: 26

United Kingdom 2005 Discovery 3 TDV6 XS Manual Aintree GreenDiscovery 3

Hey

I’m up near wick far far north of Scotland but the car is in Inverness 100 miles away from me

Even tho the high pressure fuel pump wiring is testing fine is it possible for them to still be damaged and losing the signals causing this intermittent fault cause ever time you stop and restart it , its drives fine again ? And if they run new wires that should rule that out same for the fuel pressure sensor could also be wiring even tho it’s been tested like three times , but they are also saying that they hope they haven’t damaged the wiring having the body off Big Cry

But why did the car completely stop running they where at it two days trying to get it running again but as soon as they changed the pump it’s back running again but then waits till the third day of driving to play up again , makes no sense!
  
Post #238004322nd Oct 2024 12:49 pm
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