LR3 2006 4.4ltr, fuel issues which Land Rover cannot diagnose

[shedlock2000]

Sorry for the long post which follows, but I think you need all this information to help out! I am having a protracted issue with my LR3, 2006, 4.4ltr, LHD, HSE, 120,000miles. She unfortunately became wet in a recent flood event in my town and drew in water through the fuel filler cap (The car was running and being loaded to exit the site when the bank side slipped away. The insurance won't cover any issues and I am a (now) very broke student). The inside of the vehicle remained largely dry, but she was running until she stalled from water in the fuel.

The water contained a soft fine clay particulate which clogged up the fuel pump went though the filter and into the engine. The injectors were clogged but have been replaced. The fuel tank, pump, filler cap, and evap. lines have been changed with spares from a running 2006 (fitted with a recall tank upgrade -- a straight fit, 2010 tank and pump). The battery box has had no water ingress, and I have removed the transfer case module and ECM to inspect for water ingress in the plugs or module (which there was not). The E-box fan shows as 'off' in the code reader, but a false feed runs up the fan fine. The fan fuse is good.

The problems are these:

After an hour or more of driving, or about 20 minutes of idling in hot weather, the vehicle begins to run progressively leaner and eventually stalls.
Switching off the key for 10 seconds resets the ECM and the vehicle runs fine for about 10-20 more minutes when the difficulties begin to slowly re-occur.
Switching off the vehicle for 10 more seconds will again re-set the problem for another 10-20 minutes.
The symptoms occur more quickly in the heat (especially the 35 degree heat we're having at the moment), but last night, with the ambient air at about 18 degrees, she idled for 2 hours without any difficulty then drove home perfectly.
Opening the bonnet reduces the time which the issue occurs -- however, she will still begin to fail eventually.
She seems to perform without issue much longer with a full tank of fuel -- though this may also be just a corollary, rather than a cause.


When the data streams are observed during the lean times, the short term fuel trims max out at 41.4%+ and the O2 sensors run to around 1.16mA (though Bank 1 is usually more extreme than bank 2 -- despite the fact that Bank 2 records more lean codes than bank 1). There are rarely any fault codes thrown -- even if the vehicle stalls, but occasionally a lean code for banks 1&2 are given, or (very rarely) a misfire code. When the vehicle is running normally, fuel trim figures hover around 2 or 3-4% and bounce around as you might expect, and the O2 sensors report 0.01mA and flick around properly. Sensors progress to the former slowly and progressively, and correlate with the progressive lack of power one expects from a shortage of fuel. The O2 sensors have been disconnected and codes reset then a test run has been made under which the vehicle failed again after about 10 minutes of idling and 25km of driving. From this I conclude that it cannot be O2 data which is being improperly managed by the ECM.


Work done has included:

-- Replaced O2 sensors and injectors,
-- Blown out fuel lines,
-- replaced pump and filter (and fuel tank).
-- Cats. inspected and found to be in excellent condition.
-- Battery box, Transfer case module, and ECM inspected for water damage.
-- Inlet manifold checked for leaks; the evap. system has been isolated from the engine to eliminate that.
-- Fuel tank cap has been removed to check for vacuum issues and replacement fitted.
-- Engine ECM has been re-mapped to avoid stored data glitches, vehicle taken to Land Rover (who have been unable to diagnose the fault but charged me $1000 for the privilege).
-- Inside of vehicle checked for water ingress and the passenger (LHD) carpets removed to dry and clean out wiring in the sill.
-- Battery voltage checked: good and consistent,
-- Fuel pump electrical-feed plugs under front wheelwell checked for water/dirt ingress.
-- Tank has been inspected for floating bags/plastic,
-- Fuel pump removed and bench tested,
-- O2 sensors disconnected for trial run,
-- Smoke test carried out,
-- E-box fan/fuse tested,
-- Fuel rail pressure checked (80psi)

No existing fault codes show; all historical codes have been eliminated and all systems operate normally. Vehicle ECM has been hard reset prior and after ECM hot-soak.

When the vehicle is just started or cold, it runs perfectly and without issue. However, very, very occasionally (only twice ever), there is some hesitation to start which feels like a lack of fuel too (the key cycle does not start the vehicle but there is a faint try to start. Starting the car is possible on the second cycle).


Further information:
The MAF and MAP sensors record appropriately and within parameters; the coolant temp. is about 95, and the control module temp. between 49-62C; fuel rail temp fluctuates around 50-60C.

Fuel pressure when running well is 80psi (over the 65psi required), but I have not yet run the pressure gauge while the vehicle has been running lean, as this at first only happened on long runs. The new O2 sensors seem to have contributed to a faster onset of symptoms.

When the vehicle begins to show symptoms, it first presents as a lack of power on hills or accelerating, a general hesitation and lack of responsiveness, and later as a miss; when the vehicle becomes severely affected, there is no acceleration and maintenance of speed is not possible, there is then a lot of coughing and bumbling and the vehicle cuts out. Switching off the key and waiting 10 seconds starts the car as normal and no symptoms present.

I am guessing that it is a temperature-related sensor fail, but I do not know what sensor could cause the difficulties as the sensors involved in fuel regulation have been checked or changed: the MAP and MAF report fine throughout, the O2 sensors have been replaced, and the temperature sensors report properly and accurately. Clearly the ECM is being reset and the learned data is being deleted by switching off the key, but what information is the ECM getting which causes this issue?



Any suggestions, people?
I have been advised to:

-- check the ECM fan (works fine, but is shown as 'off' by the code reader),
-- check the fuel pressure during the lean periods which requires the pressure gauge to be continually inline (not possible until my mechanic comes back from holiday and I can borrow his fuel pressure tester). This would only indicate a physical lack of fuel to the engine, not the reason for the lack of fuel (which, I am assuming would also be ECM?)

[Graeme]

I would replace the crankshaft position sensor because some of the symptoms are typical of a failing one and its a sensor that hasn't been replaced. You could try cooling the sensor with an aerosol or water spray to see if the problem is quickly overcome.

[shedlock2000]

Interesting thought, Graeme. I shall just order one as they are not big $. Just out of curiosity, which of the symptoms are the same?

[Silenceisgolden]

I am guessing that it is a temperature-related sensor fail,

When you stop the engine, at first the temperature of the block will rise due to heat soak, so I don't think it is a temperature sensitive sensor at fault. During ten seconds the temperature wouldn't drop.

You seem to have done all the sensible things - hopefully someone here can give you a clue. Very tricky.

[Graeme]

Failing crankshaft position sensors often fail to work properly or work at all when they get hot, whereby even a little rest allows them to cool enough to work again for a while. Your engine's symptoms aren't exactly the same so cooling using a liquid, if access is easy enough, might be a good move. Alternatively if not expensive nor time-consuming to change, it might be simplest to just fit a new one.

[Cambo_oldjaguar]

You said you checked the fuel rail pressure and you got 80psi...

Was that checked with an external gauge or via OBD?

80psi is too high to me, the naturally AJV8 runs at 3.8-5.0 bar normally (55-70psi) and the typical delivery rate of the fuel pump is at 3.8bar or 55psi.

The fuel pressure sensor is a differential sensor that is referenced to manifold vacuum, but if you are looking at it via OBD it should be telling you 55psi +/- a few, but not 80psi, that's too high.

If the sensor is telling the ECU that there's 80psi at the rail then it will back off the pump flow, which could cause a lean condition.

The fuel pressure sensor is not on your list of items that were replaced.

Look into that.

[Graeme]

If the sensor is telling the ECU that there's 80psi at the rail then it will back off the pump flow, which could cause a lean condition.I went looking for such a sensor in the WSM because I've encountered similar problems with such a sensor on another make, but didn't stumble on the sensor. Where is the sensor?

[Cambo_oldjaguar]

Oh wait, seems that the LR setup is different.

Runs at 65psi normally not 55psi.

And there doesn't seem to be a fuel pressure sensor in the parts list....

Strange...

The Supercharged 4.2L in the RRS & Vogue has the same fuel pressure sensor as the Jags, but seems that 4.4L is a totally different setup...

*now i'm confused*

But here it's mentioned there's a fuel pressure sensor/switch on the rail of the 4.4L http://workshop-manuals.com/landrover/lr3_(la)/v8-4394cc_4.4l/sensors_and_switches/sensors_and_switches_powertrain_management/sensors_and_switches_fuel_delivery_and_air_inducti on/fuel_pressure_sensor/switch/component_information/locations/

[Graeme]

I saw a fuel temp sensor there so perhaps its a combination temp and pressure sensor.

Edit: No, likely to only be a temp sensor judging by its low cost. Also a SC'd or turbo'd engine needs a pressure sensor relative to manifold pressure rather than atmosphere, so the pump itself may contain a pressure sensor.

[Cambo_oldjaguar]

The naturally aspirated 4.2L AJV8 in the Jags uses the exact same fuel pressure sensor as the S/C engines, so beats me why the 4.4L LR version doesn't have one.

I suppose there isn't a pressure sensor in the 4.4L it's just the regulator in the tank and the pressure is fixed. That's how it looks in this document ==>> http://www.disco3.co.uk/gallery/albums/userpics/15405/LR3_Fuel_System_Description_and_Operation.pdf

Still wonder why they measured 80psi when the system is meant to run at 65psi though...that doesn't seem right...

[Graeme]

Yes, as per your earlier comment an incorrectly high reading would be expected to result in too lean a mixture.

[shedlock2000]

Hmmm, the fuel tank replacement is a bit of a story:

I first tried to clean out and back-flush the original pump and halo-filter -- which was a moderate success. I replaced the pump into the tank, and then installed the tank back into the vehicle. This was the first effort made after the flooding.

The original pump ran up and was measured as delivering 80ps from an external gauge fitted inline with the fuel rail. This powered the vehicle for about 10 minutes on its first test drive but began to run lean and stumble. I first thought that this was caused by a shortage of fuel (hence the fuelling up), but after filing up with gas (petrol) at the fuel station, she stalled on her way out of the station. After the vehicle quit on me in the middle of lights, she started back up again after a few seconds but turning off the key and turning it back on again (though I did not know I was resetting anything at the time). She only had enough power to get me back to the shop. The following morning, we tried the car again, and she started and drove fine and we again tested the vehicle with the fuel pressure gauge inline. The gauge read 80psi, but as the vehicle started to become lean, the fuel pressure gauge lost pressure. However, all this happened within the first 5 minutes, and while still in the yard. We presumed the pump repair and cleaning had not gone well, and sought a second pump.

Sourcing a second hand fuel pump was possible and I found a 2006 donor, but when the tank arrived, it was clear that the pump and tank were different. The donor vehicle had been fitted with a 2010 tank and pump after a recall was issued on certain vin numbers. We were given the entire tank, fuel pump, electric harness and all of the evap. pipes and fuel lines. It is this tank and pump (which are not interchangeable) which is currently fitted to the vehicle -- not the original tank. The donor tank was placed into the vehicle and the fuel pressure was inspected before the vehicle was taken out of the shop; the inline fuel pressure gauge measured 80psi at idle in neutral. It is possible that the gauge is slightly out, but not excessively as it is a Snap On kit.

What is interesting from all of this, is that the first tank and cleaned pump, presented with similar symptoms (but more severe and happening sooner) than the second tank. The second tank was selected also, in part, due to the difficulty of washing out the first tank to remove the clay like sediment which would be in all of the weird baffles and plastic tubes shown in your diagram above.

Of further interest:

Tonight's test run was conducted with little fuel in the tank, and after re-cleaning the throttle body and the MAF sensor. It was only 15 degrees outside and the vehicle drove seamlessly for 50 miles without any fault presenting. However, coming into the next town the vehicle started faintly hesitating, and I turned around only for the vehicle to quit on me fully as I accelerated out of the town on the highway. Having switched off the vehicle and re-started it, I was able to drive 50 miles home before any further symptoms presented. The fuel temperature reached 63degrees, and the ECM temperatures were also normal -- The only difference between tonight's and last night's test runs, are the external temperature, and the cleaner MAF sensor -- yet last night I struggled to drive 25km after 10 minutes idling, and tonight I idled for 20 minutes and drove 80km before symptoms occurred.

I hope this information is helpful to you all -- though I am sensitive to your position on too greater fuel pressure, I find it difficult to understand why too much pressure (which is maintained by the pressure regulators inside the tank and pump) would sometimes permit the car to drive for 2 hours or more, and sometimes only 25 minutes.

There does seem to be an ambient air temperature correlation: The more fuel in the tank, the longer the time taken for issues to present. The colder the ambient air, the longer it takes for symptoms to present.

After speaking to a friend in the UK, I have ordered a new MAF sensor (hence the re-cleaning tonight) -- but after tonight's performance, I am reluctant to believe it is the MAF. Indeed, I have ordered a CPS as well as a MAF, but I cannot actually source any other relevant sensors in the US other than the throttle position sensor (which I am reluctant to try at $591).

[shedlock2000]

I suppose there isn't a pressure sensor in the 4.4L it's just the regulator in the tank and the pressure is fixed. That's how it looks in this document ==>> http://www.disco3.co.uk/gallery/albums/userpics/15405/LR3_Fuel_System_Description_and_Operation.pdf



This is really helpful, Cambo. Thanks! Do you think it would be possible to steam out the original tank properly without damaging any of the internal components (once the fuel pump is removed). The clay is water soluble, but not soluble in fuel (it turns into a gloopy paste which clogs everything up). I am contemplating buying a new fuel pump and putting it in the old tank (fewer ROV and evap. nonsense), but I am concerned about the level of clay dirt in there.

[Cambo_oldjaguar]

I wouldn't use steam to clean out the tank. Hot/warm water but not steam. The tanks are made of plastic and getting them too hot wouldn't be good for them.

The fuel pressure regulator is meant to give you 65psi, but it's giving you 80psi instead. Why?

It seems rather implausible that high fuel pressure could cause fuel starvation, but you are chasing a weird problem, and here's one thing that is "out of spec" so you can't rule it out until it's "within spec", in my opinion.

I've been told that it's not unheard of for injectors to not open properly if there is too high a pressure pushing against them AND there is a driver / power supply issue to the injectors themselves. I would not expect this to happen with these modern injectors in an AJV8, but you never know...

So the high fuel pressure would not be the cause, but it could be a contributor... maybe...

Have you checked that the injectors are actually opening & cycling as they should? the power/signal to the injectors is good & strong?

You said you've had the ECU "re-mapped to avoid stored data glitches" why? what was done exactly? The ECU files were modified? or just re-flashed with the standard files?

Highly doubt it could be related to the TPS. They either work or they don't (running fine or limp mode, not really anything in between).

[banarcus]

There should be a purge solenoid that lets the engine breathe in fuel vapour from the fuel tank. If the solenoid is not working properly, as in an open state for example, it will let in unmetered air and may cause a lean fuel state or at least poor idle and drivability issues.

If you haven't already done so, isolate the solenoid and block off where its hose meets the inlet manifold. For the time being, let the fuel vapours vent naturally ie, into the atmosphere. Reset the engine management and go for another drive.

There is clearly a relationship between ambient temperature and the way your rig operates and the purge solenoid may be to blame as the fuel vapour in the tank increases with outside temperatures. Give it a go and report back.

[shedlock2000]

I wouldn't use steam to clean out the tank. Hot/warm water but not steam. The tanks are made of plastic and getting them too hot wouldn't be good for them.

Gotchya. Theres a rad cleaning place that I was thinking of taking it too -- they do tanks too. I was concerned about the front fuel sender which I cannot get out.


The fuel pressure regulator is meant to give you 65psi, but it's giving you 80psi instead. Why?

I am not sure -- the other pump on tank 1 read about that too -- it is possible that the gauge is a bit out -- but 15 psi is a fair margin! I shall double check when my friend with the pressure gauge returns from holidays.



Have you checked that the injectors are actually opening & cycling as they should? the power/signal to the injectors is good & strong?

No, I have no tool to check this. I know the injectors were cycling properly at Land Rover -- though when we ran the tests there, the injector delay was only 7ms, even though we she was running to the point of stalling in the shop. My code reader does not look at injector times. The injectors were replaced with used ones, but off a running vehicle. The electrical plugs were checked when we changed the injectors -- but I have no harness or mechanism to check the ECM pulses to the injectors -- I am working on a bit of a shoestring budget as I am a student, and I have already dumped $2500 into her to try and fix her, and I am no better off now than when I started. .


You said you've had the ECU "re-mapped to avoid stored data glitches" why? what was done exactly? The ECU files were modified? or just re-flashed with the standard files?

The ECM was flashed with standard files. I wanted to ensure that there was no logging of improper data due to any spurious data from the flooding. The ECM took the flashing with no issues, which helps me think that the ECM is not at fault (I'd have expected difficulty with the flashing if there were ground issues or something with the ECM).


Highly doubt it could be related to the TPS. They either work or they don't (running fine or limp mode, not really anything in between).

No, I don't either -- but I want to check every fuel related sensor. If I rule out all of these sensors, it has to be fuel supply -- but I've never heard of a resetting fuel supply issue!?

[Cambo_oldjaguar]

Hmmm....

80psi - 65psi = 15psi which is about 1 atmosphere...

Is the gauge they're using an "absolute" pressure gauge by any chance?

[shedlock2000]

Hmmm....

80psi - 65psi = 15psi which is about 1 atmosphere...

Is the gauge they're using an "absolute" pressure gauge by any chance?

I'm actually not certain! I can't check until Monday when my friend (the owner of a shop, returns from holiday. What are you thinking?

[shedlock2000]

If you haven't already done so, isolate the solenoid and block off where its hose meets the inlet manifold. For the time being, let the fuel vapours vent naturally ie, into the atmosphere. Reset the engine management and go for another drive.

How do you reset the engine management?


There is clearly a relationship between ambient temperature and the way your rig operates and the purge solenoid may be to blame as the fuel vapour in the tank increases with outside temperatures. Give it a go and report back.

Yes, this had crossed my mind, but I didn't think it would be enough to stall the engine. I've actually ordered the purge valve, and shall inspect the carbon canister while I'm at it. Can you tell me where the engine draws in the evap. air? Maybe I've missed a hose..... The one I disconnected was in the hose before the throttlebody.

[banarcus]

I don't know where it plumbs in sorry, but it should be after the throttle body.

[the_preacher1973]

I'm actually not certain! I can't check until Monday when my friend (the owner of a shop, returns from holiday. What are you thinking?

I believe he's thinking that if they're using an absolute pressure gauge it may be adding in the 15 psi of normal atmospheric pressure so you get 65 +15 = 80 which means it is actually within spec and this is a red herring.

[shedlock2000]

I believe he's thinking that if they're using an absolute pressure gauge it may be adding in the 15 psi of normal atmospheric pressure so you get 65 +15 = 80 which means it is actually within spec and this is a red herring.

Ahhhh! Understood. I don't know -- but I will find out Monday.

[shedlock2000]

Update!

Fitting a new MAF did not resolve any of the faults.

But I think I have found the problem. I launched all items in the code reader, and went through them one-by-one when the problems were absent as well as when the problems were manifest. The main distinction is that when the vehicle starts to run poorly, the Engine Output 1 - Fuel cut off was ON This explains all of the faults.

When I cycled the key, the vehicle started, but the fuel cut-off hesitated between ON/OFF (flickered between 'ON' and 'OFF') a few times and then stayed 'OFF', and the vehicle ran perfectly. Concordant with the fuel cut off being 'OFF' was a strong pump sound heard through the filler cap -- when the cut off was 'ON' the pump was noticeably quieter and seemed to be struggling.

The fuel cut off does not seem to be complete, but I am unfamiliar with how the ECM controls the cut off and by what mechanism it does it. There is a strong correlation with Ambient air temperature, or fuel temperature -- what can affect fuel cut off that is temperature related?

The Engine Output 1 - Fuel Relay is permanently 'OFF' and is throughout the testing -- either when the vehicle runs well or runs rough. I would have thought this should be 'ON' when the vehicle is running. I also heard the E-box fan running when the code reader clearly shows it as being 'OFF'.

It seems to me that the fuel cut off seems to develop a partial feed to partially activate it -- any suggestions?

Can someone please provide me with the locations of the grounds that the ECM uses for switching (especially for anything it grounds relating to the fuel system). I have read the document that was kindly provided -- but it does not mention anything about fuel cut off. (I am assuming there is nothing obvious like an old Ford-style inertia cut of valve that might have become wet?)

I should finally point out that with the vehicle running, removing the fuel relay causes the vehicle to stall shortly afterwards, so the fuel relay is working. I have also switched it for another relay of same type to check the relay itself.

[Eevo]

some great differential diagnosis.
keep the updates coming.

[banarcus]

Can you check to see if the fuel tank pressure sensor functions properly too? That will have an affect on how your ECU determines fuelling.

[shedlock2000]

Can you check to see if the fuel tank pressure sensor functions properly too? That will have an affect on how your ECU determines fuelling.

Thank you for the guidance. I can check the operation of the fuel pressure sensor, but I am not certain that there is one inside my tank. The wiring schematic I have for the tank shows no pressure sensor (I was taken to understand that the pressure regulation was a mechanical on the pump itself and was not monitored electronically).

Do you know where in the tank this would be? I am assuming that any data it provides must come out of the multi-electrical plug on the top of the tank?

[shedlock2000]

I have been told that Land Rover observes:

"If there is a process fault in the ECM, the ECM either uses fuel injection cut-off to limit engine speed to 1300 rev/ min or disables fuel injection*to stop the engine."

This sounds like it might be the issue. I find it hard to believe that there has been an ECM fault, and much more likely to be some sensor or transistor breaking down under heat as the correlation between the ambient air temperature and the symptoms is clear.

Would anyone consider a dodgy ground to/from the ECM to be a potential issue?

[LandyAndy]

When I did the Green Oval Experience seminar Gordon mentioned 3 electrical connections that cause issues when they get wet.From memory,the gearbox/transfecase ECU under the bonnet,wich you said is ok.The others were near the air susp compressor and above one of the rear struts near the fuel tank.He reccomended electrical sealant to be used in these areas.Worth checking/cleaning.
Andrew

[shedlock2000]

Ok, here's the deal. The symptoms are generated by the ECM output 'fuel cut off' which flickers ON and OFF, then eventually stays ON.

[B]Apart[B] from the ECM, what could cause tris issue -- especially one which is temperature related (though the flickering happens at start up for a couple of seconds and then settles down). I'm thinking its a grounding issue.....

[rangeyrover]

I've read with interest the fault finding on this.
However I think that you may be off the path with the last part.
If the ECM is deciding that Fuel cut off is required, as observed on the code reader, you need to find the reason for that.
My view is that the ECM is following it's code to get to that point (FCO active), not that there is a ground issue causing it to become active.
Can't help you with the reason tho, sorry.
RR

Edit: unless the FCO line is a sensor, rather than a control.
In other words the FCO becomes active and that is then sensed by the ECM
Maybe this electrical diagram can help? (http://www.vw8848.net/view_8s278qyfycjhwmu1.html)

[shedlock2000]

[quote=rangeyrover;2403904
Edit: unless the FCO line is a sensor, rather than a control.
In other words the FCO becomes active and that is then sensed by the ECM
Maybe this electrical diagram can help? (http://www.vw8848.net/view_8s278qyfycjhwmu1.html)[/quote]

From what I am told, the FCO is an output from the ECM which reduces the injector opening to limit rpm. It's actually not doing this very well as the fuel seems to be restricted -- rather than cut off. In other words, the cut off become progressively worse rather than OFF.

I have noticed, though, that the FCO triggers to 'ON' as the key is turned to start started (twice, in fact), though this 'ON' only lasts for an instant. On reflection, it seems like the ECM is looking for information during start up, and switches the FCO 'ON' when it doesn't find it -- then it seems to get it and be happy until something on the engine or fuel side heats up enough to trigger the coming 'ON' again. I wondered if the ECM is having issues grounding the sensors it receives inputs from, and if this is the reason why it decides to cut fuel?

[shedlock2000]

Maybe this electrical diagram can help? (http://www.vw8848.net/view_8s278qyfycjhwmu1.html)

Thanks for this great resource!! Its for a RHD (mine is LHD), but its still going to be extremely useful. I wonder, do you have access to the location points for the grounds and sensors etc? I believe its in the workshop manual under 'Locations'. But it is not listed in the wiring diagram.

[letherm]

Thanks for this great resource!! Its for a RHD (mine is LHD), but its still going to be extremely useful. I wonder, do you have access to the location points for the grounds and sensors etc? I believe its in the workshop manual under 'Locations'. But it is not listed in the wiring diagram.

Hi.

You may find this useful. Full workshop manual collection for D3 etc. D3 currently $18.50. DavesITShop is run by the owner of this site Incisor. You'd have to ask him via PM whether he can/will post overseas but the cost is $18.50 Australian. Might be handy to have for future reference even if not now. I have just bought the D4 version and, from my initial scan, it looks like it contained all the wiring diagrams and error codes as well as the usual workshop manual content. It also had the drivers manuals.

https://www.davesitshop.com/emporium/manuals-cd/dvd.html

Regards,
Martin

[shedlock2000]

Thanks, Martin. I'll absolutely get in touch with him about this. I have a ten-day window in which to fix my LR3, so it may not work for this issue, but it'll certainly be handy! Thanks for the suggestion!

[shedlock2000]

Update:

After a day of exhausting testing, here is what we can say for sure:
Physical fuel pressure at fuel rail drops progressively from 62psi to 20psi whereabout the vehicle stalls.
Fuel pump has been supplied with a false feed (bypassing the relay) and problems still present.
Fuel pump is audible when pressure is good, fuel pump is not audible when pressure is low.
Fuel pump grounds and feeds have been checked.
ECM switches on its Fuel cut off 'ON' about the same time that the pressure can be seen to drop (why her it causes the fuel pressure drop, or responds to it is unclear).
Fuel problems reset when key is cycled -- sometimes it resets after 1 cycle -- sometimes it takes a few cycles.
All ECM grounds have been checked and are good; fuel pump feeds have been checked and found to be good and continuous.

All this seems to point to a fuel pump, but has anyone heard of a resetting fuel pump?

[Eevo]

almost like there is a resistor build up in the fuel pump until its de energised.

[Cambo_oldjaguar]

Have you got a clampmeter that can measure the current going to the pump, just clip it on to the power feed to the pump. Also monitor the voltage too.

Not sure exactly what sort of amps it should be pulling normally, but if you can see what the difference is from when it's putting out 60-odd psi and when it drops, might be useful to know.

I can't seem to download that wiring diagram, is this one of those PWM driven pumps with a variable speed? Or should it just run at the one speed?

[shedlock2000]

I can't seem to download that wiring diagram, is this one of those PWM driven pumps with a variable speed? Or should it just run at the one speed?

I'm not sure what a PWM pump is. The physical item just has two wires and looks like any other pump. Surprisingly, it's not a screw pump but sounds like a solenoid pump. That's all I can tell you. According to the wiring diagram I have, it's just one wire to the pump from the pump relay. The ground disappears up the back 'D' post. There seems to be feeds to a pump leak detection module -- but I think that is an evap. thing.

[Cambo_oldjaguar]

PWM = Pulse Width Modulation, instead of a flat DC voltage it's a square-waved pulse signal, used to control the speed of a fuel pump.

But if there is a just a relay switching the pump on/off then it's just going to be a plain DC voltage and the pump has just one speed. Much simpler.

So my question is what's going on with the power supply to the pump, is it stable? Is the current consumption of the pump "normal"?

But it does sound like the pump is failing as it warms up. This would also fit with what you said about it taking longer to happen with a full tank of fuel.

I know i'd be reluctant to throw a new fuel pump at it without being sure...

Have you measured the resistance of the cables to the pump?

[shedlock2000]

So my question is what's going on with the power supply to the pump, is it stable? Is the current consumption of the pump "normal"?

Yeah, the voltage is a stable 13.2, as is the amperage drawn by the pump: it starts at 5.2A and peaks at 6.4A; it settles down to 5.75A


But it does sound like the pump is failing as it warms up. This would also fit with what you said about it taking longer to happen with a full tank of fuel.

I have put 4 gallons of fuel in tonight to test the theory (while it was playing up) and it didn't make much difference. I also stopped and quickly exchanged the fuel relay for a jumper line and that didn't affect it either. What I can tell you, is that the fuel pressure was all over the place this evening after we got the engine hot by idling. The pressure would start of the key at 62psi then steadily drop to 50 psi. It had a moment of dropping to 30 psi, but after about 1 minute jumped up sharply back to 62psi. It's now hovering at idle between 45 and 55psi. When the pressure drops, the fuel trim alters to suit.


I know i'd be reluctant to throw a new fuel pump at it without being sure...

Tell me about it! She's had $2500 on her already, and this will be the second pump I'm thinking of putting in. I don't know how long the LR3 this tank and pump came out of was stood, but I can't see that affecting the pump badly -- unless they had drained the tank early on and the pump dried out? That doesn't explain the reset, though. What I think might, is a faulty pressure regulator on the pump. If the pressure regulator is failing, then it's possible that the few seconds that the fuel pump is off is enough for the mechanism to return to normal and then take time to fail open and release fuel into the front push-pump in the tank.


Have you measured the resistance of the cables to the pump?

No, it's impossible to do without dropping the tank. I shall order a pump tomorrow and measure the resistance in the feed wires then. Unless you guys can think of anything else, I'm running out of ideas now.

Good voltage, good amperage, no difference between the relay and a jumper lead over the electrical supply, good grounds for the ECM, fuel pump, and for the engine. But poor and varying fuel pressure at the fuel rail reset by a key cycle (though the hotter the engine and fuel the more quickly the symptoms recur).

The ECM fuel cut off 'ON' cannot be contributory as the fuel rail pressure is what fluctuates -- the cut off reduces the dwell time on the injectors.

[rangeyrover]

Can you run the fuel pump on its own, through the pressure reg into a fluid resistance?
Semi Clamped hose maybe?
This would prove the fuel pump one way or another if it fails or loses pressure after running for a bit.
RR

[shedlock2000]

Well, folks, I don't think you will have expected this response, but I think I have fixed it by replacing the fuel pump. More accurately, I think the replacing of the fuel pressure regulator has fixed the issue. I drove 160 miles at 40 degrees into strong wind, and she didn't miss a beat.

On the downside, I snagged a sensor float on something, as she reads 1/2 full or more all the time, and I have lost my front jet pump somehow (though I think that has happened because I pushed the free corrugated tube onto the blanked off fitting on the tank cover plate. I now think that hose must be the return from the front jet pump).

Tank is coming out Monday night to further rectify the issues I have engendered.

[Cambo_oldjaguar]

Well thats some good news. Very close now :)

About the gauge not reading right, I had the same problem when I changed the pumps in one of my Jags. When tightening the locking nut that holds it into the tank, the one of the pumps turned with the nut and the float arm was not in the right position & got caught up on something. Is there an arrow on the top of the pump that's meant to be pointing forwards?

[shedlock2000]

Is there an arrow on the top of the pump that's meant to be pointing forwards?

I'm not too sure. The pump does not seem to sit in its housing in any other way than it does as there is a flat on one side of the pump and a groove in which another location mark sits. I have a feeling that it is the front sender float which is caught on some of the framework within the tank. I'll have to have a feel as you can only get that sender out by shoving your hand into the tank to feel the part. It may not have been properly mounted. Either way, I think I am going to replace the two senders while I have the tank out. Both tank floats have fairly aggressive wear marks in them -- so it seems like they may catch on something when properly fitted!

[LandyAndy]

Good to see persistance pays off.
Hopefully you have fixed it and helped others into the future by your work.
ENJOY
Andrew

[shedlock2000]

Here we go folks:

The fuel pressure regulator was faulty permitting the pressure relief valve to drop to its proper (closed) position when the fuel pressure dropped as the pump was switched off with the key. The recent fuel issues were caused by not remembering how the tank parts were fitted due to the 3 months in-between fitting the removing the original tank and removing the replacement tank last week. The rear fuel sender had become faulty and was reading improperly. The stalling when low on fuel was due to accidentally blocking of the front jet pump return pipe instead of it mounting it in the clip on the top of the fuel pump.

All symptoms have now been eliminated.

Part of the difficulty in locating the fault was down to well respected mechanics and advisers being very sure that fuel pumps do not present as resetting and so ruling it out from our differential diagnosis when, it seems, that fuel pump regulators are able to reset if bypassing fuel at too lower pressure.

Thanks for all of your help, folks -- and I hope that this issue will be a much more easily solved issue if people ever come across it again! It has taken me 3 months and a week to resolve this issue and it has cost me $2200CAD in purchasing of unneeded parts and $600 for the correct part. I am fortunate to have a friend with patience and a shop who has helped me at night to go through all of these potential issues. I have racked up 57 hours of ramp time over three months -- charged at shop price here in Lethbridge, that would have been about $6500 on top of the parts cost.

[Jimhunt]

My lr3 v8 is having similar problems as yours. Infact nearly everything is the same so I replaced the fuel pump as well hoping my problems would be gone, but no. I’ve just replaced the ignition coils but still the same. It feels like it’s not getting fuel. I parked it in our driveway the other day which is a decline. It had over a quarter of a tank of fuel and it wouldn’t start. I put around 30 litres of fuel in it and it fired up straight away. In this post you mention a jet pump at the front of the fuel tank. Does this fail? When I replaced the pump I refitted everything back how I removed them (I think) . Should I take the tank out again and check everything but this problem existed before I fitted the new pump. Just needing some advice please.