TD4 Fuel Problem MIL light comes on

[BigTwig]

Hi, car is a 12/03 model Freelander TD4, 123K. Please help, this car has just ruined my day.
This started when I noticed a pulsing/surging on mid throttle and there would be an increased detonation/pinking noise. After cleaning the EGR valve with no difference, I thought it could be a fuel delivery problem, so bought a new Bearmach filter and fitted it. Problem persisted so, foolishly I bought a new, £35 pump from Ebay. The first new one was very noisy, and the replacement would not let the engine rev fully. This got worse over a week of use until it would not rev past 2500 and the Mil light would come on, but would go off again.
So I put the original pump back in, but it stayed un-revable.
Went to MJ Fews and bought new LR pump and filter. Fitted pump and for 2 miles, seemed fine, then the fault retuned. I fitted the LR filter, but no difference.
I've tried removing the LP sensor connection, and it revved better, up to 4k, but if you drove the engine would die. Cleaned connections with switch cleaner on LP sensor and HP rail sensor, but no joy.
Whilst at Fews they put it on their fault code reader and there are a few, and they cleared them. Some were from me disconnecting things:
Low side fuel sensor plausibility 0x1260
T21 Boost Ait Temp sensor 0x1110
Fuel rail pressure sensor malfunction 0x0190
Pressure Regulator valve malfunction 0x1195
Camshaft position sensor malfunction 0x1e25

They cleared them (this was before I fitted the LR parts) but the Low Pressure 1260 fault immediately returned. Low pressure supply was 204 kPa at tickover and 136 kPa at 2700 rpm.

So.... new parts in, connections all clean, fault persists. It now wont rev above 1500. Any help really, really, really appreciated!!! This is ruining my Easter

 

[john t]

fuel pressure problem ? ,as im sure you are on the right track
1, have you tried a fuel flow test at the filter outlet or before the hp pump
2, injector leak off test
3, as you have been getting regulator faults, the regulator is attached to the hp pump, not sure how you can test this, most prob have to eliminate by replacement, it removes quite easily 2 small bolts, you could take it off and check the seals are intact
4, fuel rail pressure sensor/ wiring harness

do you have a intank pump ?

 

[BigTwig]

1, have you tried a fuel flow test at the filter outlet or before the hp pump

When I changed the filter and LP pump the final time, I ended up with the whole tray off the car, with sedimentor which I emptied. I applied my own 12v supply to the new parts with the tank pipe connected, but the engine outlet going in to a bowl. Fuel burbled through and after a few seconds started to gush into the bowl. I have not pressure tested this - no equipment to do so.

2, injector leak off test

The garage suggested that if it's starting OK, it's probably not a leaky injector fault. It starts right away, but as I'm running out of things to check, this could be next...

3, as you have been getting regulator faults, the regulator is attached to the hp pump, not sure how you can test this, most prob have to eliminate by replacement, it removes quite easily 2 small bolts, you could take it off and check the seals are intact

Good idea. Is this the LP pressure regulator? I have read posts of this being replaced, or at least a new seal, but the fix rarely seems to last. Anyway, worth a look.

4, fuel rail pressure sensor/ wiring harness

I have the replacement type, with a new cable through to ECU. Both ends checked for good connection. In fact, my last post was asking about the spare plug that this left near the sensor. I opened the ECU box and can see the 3 wires and pins that are left free there from the old harness. It's out of circuit.
Thanks for help, looks like another day to smell of diesel!!

 

[BigTwig]

Anyone know how to measure the value of the LP fuel pressure sensor with DVM or 'scope? No idea what the value should be. Also, any DIY methods for measuring low side fuel pressure? Thanks.

 

[john t]

point 1, you need to establish the lp pump is delivering fuel,to the hp pump, by putting your own 12v supply to it you have bypassed the cars circuits , can you be certain it is actuallly functioning correctly, blown fuse / relay ?.
2, injector leakoff, however unlikely, could be enough to reduce pressure at the fuel rail, ,
3, regulator testing , i dont have any data, but its possibly the last thing i would suspect i think it works like a relief valve, getting a signal from the fuel rail sensor via the ecu, but dont quote me on that.

these faults are a pain and quite time consuming to locate, i have overtime acquired all the sensors, and an arm full of spares which i can use on an elimination process, as i will never use a garage,and i intend to keep my freelander for another 9 years, i prefer to spend a few quid on the tools and a few items to sort the job myself, ebay is your friend you could buy the parts and if it turns out that was not the problem they can be resold,

remember the td4 is a simple diesel engine, complicated by the technology and we are still all learning how to deal with it ,
keep us informed of your progress ,

 

[Tannaton]

3, regulator testing , i dont have any data, but its possibly the last thing i would suspect i think it works like a relief valve, getting a signal from the fuel rail sensor via the ecu, but dont quote me on that.

It is exactly that, unlike many other common rail systems the fuel pressure at the rail is controlled by bleeding off fuel from the output of the HP pump back to the tank rather than off the rail itself.

Another give away symptom relating to the fuel pressure regulator is the engine running on after you switch it off. The engine shutdown is controlled by the fuel pressure regulator opening fully so the fuel pressure at the rail immediately drops. Even with the ignition switched off, as long as the engine is turning the injectors will fire so if there is still fuel pressure the engine will run. This is to ensure the system is not left pressurised with the potential of fuel weeping through the injectors into the cylinders. The fuel pressure regulator bolts on to the back of the HP fuel pump with 2 torx screws.

 

[BigTwig]

Aha! Before I swapped out my Ebay LP pump for the LR one, the engine did once run on for a second or two. I thought that was odd at the time and wondered how that could happen. Well that's another pointer towards the fuel pressure regulator then. Thanks very much, cheered me up!
OK, next question. I have access to a Rover 75 TD4 with good engine (but off the road). Do I swap out the regulator as is (checking type) or do I find new seals for mine (assuming that's the fault) ?? Thanks again!!

 

[BigTwig]

Argh. A rather despondent update. I've taken the regulator off the HP pump and changed the green O-ring to a new black one from a kit of various sizes, it's a pretty good match and is fuel tolerant. Cleaned manifold (what a job! I used the oven cleaner technique) put it all back together and... it's exactly the same. Revs gently up to about 2500rpm, and limits there with the MIL on :-(
Next up, after a cuppa, is to break into the LP fuel hoses in the engine bay and see what the flow (to and from) is like. Any idea of the rate I should expect (to and from engine) with 1. The ignition on and 2. The engine running?
Some pics of strip down attached, inc a rather gummed up boost valve!
Thanks!

 

[BigTwig]

Ok, another test. I unclipped the fuel return hose where the screwdriver shows in the attached pic. This is on some sort of coupling that I believe diverts return flow through the cooler before going back to the tank. I've only tried it with the ignition on, not engine running, and so the LP pump is on but at about half speed (it seems to step up to full speed a couple of seconds after the engine starts). There was a reasonable flow and I assume there should be? I'd guess at 100ml in about 5 seconds? How does this sound? Anyone?

 

[BigTwig]

Bad form I know to keep replying to my own post, but hey. I decided to have another look at the LP fuel sensor which on on the near side inner wing. I tried unplugging it again, and as before, the engine is the able to rev right up to the red line with no MIL light. However, if you drive it then within a 100m and as soon as, there's some load, the MIL light comes on and then engine then dies completely. This gets worse as you drive it, with restarts until it's really not happy to rev at all. Reconnecting the LP sensor gets me back to square one, max revs 2500 at idle, less under load.
Tuesday looms, and the chances of this car getting me to work are diminishing :-(

 

[BigTwig]

Just removed the LP sensor (or whatever it is). Pic below, and as you can see, the bolt with top clamp holds it together and it comes apart easily. Anyone have one to measure statically or know where to get one (yes, I'll Google it in a sec)?

 

[john t]

Just removed the LP sensor (or whatever it is). Pic below, and as you can see, the bolt with top clamp holds it together and it comes apart easily. Anyone have one to measure statically or know where to get one (yes, I'll Google it in a sec)?

hi bigtwig i see you have had a busy weekend,i have been away from pc, so no able to contribute,
your lp pressure sensor is slightly different to mine, as mine is incorporated into the fuel filter housing mounted on the inner wing, when i disconnected mine i wasn't able to even start the engine,
i see you have found the map sensor rather fouled up, this is what controls the turbo boost so another area worth checking, also that the turbo vanes have not stuck,

 

[BigTwig]

Thanks, strangely I haven't any complaints about the turbo. My previous car, a Seat Toledo had the variable vanes and that kept getting jammed on max, causing overboosts.
Back to the Freelander, I still have a thought that it could be a fuel pickup issue from the tank. I will attempt to make a duplicate can of fuel with spare pump and filter feeding right into the LP pressure sensor. That way I can eliminate the tank pickup and even collapsing pipes from the investigation. Trouble is, I don't know what the flow rate should be, and although I know it should be about 30psi, I don't have a fuel tolerant pressure gauge either. Have thought about cannibalising a foot tyre pump for the pressure meter. Might work for a minute or two?? What's the worst that can happen? I end up covered in diesel.. again! Anyway, I tap this message out from the train. Hippo - 0, Public Transport - 1
Laters.

 

[Tannaton]

Aha! Before I swapped out my Ebay LP pump for the LR one, the engine did once run on for a second or two. I thought that was odd at the time and wondered how that could happen. Well that's another pointer towards the fuel pressure regulator then. Thanks very much, cheered me up!
OK, next question. I have access to a Rover 75 TD4 with good engine (but off the road). Do I swap out the regulator as is (checking type) or do I find new seals for mine (assuming that's the fault) ?? Thanks again!!

If you get chance to substitute it then I think it's worth a try. It's not very scientific but if you have had issues (albeit intermittent) with the engine running on for a few seconds after turning it off then it is likely you have a fuel pressure regulator issue.

I had a problem with mine where the MIL lamp would come on when overrunning the engine (engine braking) and it would run on after you turned it off. I took the regulator off, cleaned it, tapped it on the bench, replaced it and it's been cured since (6,000 miles, 3 months) no idea what I did.

I don't think it is possible to do any work/servicing on the fuel pressure reg, and I think they are hard to get - most breakers want to sell them as part of the HP pump.

 

[Supun]

well my 2002 td4 Freelander MIL lamp come on and i went for a scan, mechanic told me that it's rail pressure sensor (hp) needs to be replaced, it's engine running on after i switch it off too, so i guess if the rail pressure sensor fails, that happens too? so better check the pressure sensor too, voltages on pins can tel if it's working fine or not.

i'm only a newbie, hope this hleps

 

[BigTwig]

Thanks for the suggestions. Just wanted to post an update. Rather than start shelling out for replacement sensors, I bought a fuel injection pressure test kit from Machine Mart for £42 which I'm very pleased with.

Clarke CHT713 Fuel Injection Testing Kit – Test Port - Machine Mart

So I wanted to establish what pressure I should have on the input to the HP pump. The kit has a variety of connectors but unfortunately the FL does not have a schnaeder type valve that it would couple onto, but it did have a nice T-piece and stubs of fuel hose, so adding the T was easy (as pictured).
So the results.....
20 psi with ignition on, engine off.
Dropped to 10 psi with engine running.
Dropped to 8 psi after blipping the throttle a few times.
All pressure drops to zero as soon as engine and ignition off.

Well, from this page: Freelander - Fuel Systems - Land Rover

..it seems like I should expect to have at least 30 psi, so it already seems low. This proved to me that at least the LP sensor was not telling porkies and the LP side really was too low in pressure.
So next, I blocked the return after the HP pump to the tank and measured again, with just ignition on. 40 psi and dropped to 20psi after ignition off and a very slow drop after that.
This made me think that the LP side is OK, but that either the injectors or LP regulator (on back of HP pump) was at fault. I did a leak off test for all injectors and they were fine, at least at 20 psi they were. All the fuel going back to the tank seems to be as a result of the LP regulator.
I removed a known good regulator from my donor engine (Rover 75) and fitted. Pressure results are now:
22 psi with ignition on, engine off.
12 psi with engine running.
Argh. Still no good. Things I will try tomorrow:

1. Gently restrict the fuel return pipe to see if I can raise the pressure to 30 psi, and then see if it revs OK.
2. Test the continuity of the harness from regulator through to ECU.
3. Disconnect the fuel tank feed and use a compressor to blow back into tank which may dislodge any crud that could restrict flow.
4. Buy a Honda. Nah, not really But I do need to fix this, I'm not doing another week of public transport!

 

[ming]

Hi Twig just bin reading this and sounds like you've had some ****e , ok try this Ming test method [I'm er rockit injunear] put your hand on the lp pump inside cab on rhs ,get a helper to turn on ignition [yes i know its a doozle] you should feel the pump vibrate for about 8-12 secs then stop ,the stop means the hp sensor has been enabled . . . .this is good, if it keeps running ,could be a jammed relay , blocked pipe, or hp sensor faulty, if it does not vibrate then check fuse relay or lp sensor , you have two lp pumps on your model one in tank or rear wheel arch and the one that you were told to stick your hand on, now both these pumps are fed by the same fuse and relay and respond the same way with the sensors, these pumps are known to go intermittent [sometimes jam] if anyone jams then it will cause problems, another good test is to disconnect by the fuel filter turn on ignition and you should get a good flow straight away any foaming or splutter is a sign of a pump problems, the rear pumps are known to have crud build up , hope this helps and sorry for late reply but i have bin stuck on another planit for a long time now . . . .Ming the merfiless

 

[sijwhite]

If it's not fuel, it could be the other part of the equation... Air. Check your MAF sensor and air filter.

 

[BigTwig]

At last! Problem solved!
So just to complete the story, I tried to check the regulator wiring through to the ECU but couldn't find the wires. There was 12V and 3V on each of the regulator pins with ignition on, which I now know must be OK.
I couldn't restrict the flow on the return pipe to 'up' the pressure.
I did use a foot pump to blast back any crud into the tank prior to the rear pump/filter/sedimentor, but I don't think that was at fault. Then I found it. One of the plastic pipes that feeds the input to LP pump has a 2" extra of rubber pipe that gives it some extra flex. With the pump energised, if I squeezed this pipe, the note changed dramatically. When I removed one end, I looked inside to find.... some plastic that had almost blocked the pipe, just letting a small flow through! I thought it may have been a protective end cap from one of the filters or pumps that I've tried, but they were hard PVC and would not have fitted even if I tried to force it!
You can see this in the attached pics. I can only guess this has come from the tank, or was a pipe strengthening part that helps a joint. Anyway, snout nosed pliers removed it, all back together and.... 40+ psi of pressure with ignition on and 30 to 42 psi with engine running and revving.
And yes, it now revs fully and no MIL light!!!
I hope this story helps others, and I must say having the pressure meter helped, and now knowing the correct ball park fuel pressures would help.
Thanks to all that gave advice and moral support

 

[ming]

Well done Twig glad you got it sorted, you was always on the right lines but who would have thought a bit of plastic in the fuel lines. . . . . . any good at fixin rockit messerators