Rhythmic loss of power under load - new common rail Defender

[Billj18]

I have a two year old Defender 130. After a real shaking on corrugations I experienced a rythmic power fluctuation under load. This occurred in January. It got so bad in March it stopped the vehicle. I replaced a filter and things seemed OK. Problem then returned but mildly. I recently travelled the Great Central Road and broke down completely it got so bad. Got going again by pressurising the tank and limped to Albany Land Rover to replace the fuel line from the tank to the filter - thinking this might be damaged. Albany LR said no damage. All OK for 3000km then after another good shake-up on corrugations the problem returned. Has anyone experienced anything similar?
Bill

[TimNZ]

Bit of an odd one Bill. Certainly sounds like a fuel problem, like air is being introduced into the system. Has the MIL (engine warning) light come on?

Cheers,

[Billj18]

Thanks for reply Tim. No the MIL light does not come on when I have this problem.
Bill

[Billj18]

Another thing Tim. I agree that it is likely to do with air getting into the fuel system. There is a green plastic screw top on a brass thread at the very top of the fuel delivery line - before it goes down to the injector pump. Do you know whether this is also an air bleed valve and should it it let out air before the fuel goes down to the pump? The mechanic from Alice Springs LR who helped me when I had broken down on the Great Central Road said the problem sounded like air going into the injector pump which makes it shut off allowing the air to go back up the line, then when the injector pump comes in again it drags the air back in - and so on. It sounds logical.
Bill

[Tombie]

You may well need to drain your tank, pull the pump and clear the filter in the bottom...

Sounds like the corrugations are stirring the bottom of the tank up and blocking the pump.

[Billj18]

Thanks Thombie. I removed the tank beside the road when we broke down thinking the same thing. But there is no pump in the tank in the common rail models. Just a pick-up and guage. And it was pretty clean. The fuel delivery is via a lift pump in the motor compartment. I suspect air in the system.
Bill

[Billj18]

Sorry. Tombie.
Bill

[TimNZ]

Another thing Tim. I agree that it is likely to do with air getting into the fuel system. There is a green plastic screw top on a brass thread at the very top of the fuel delivery line - before it goes down to the injector pump. Do you know whether this is also an air bleed valve and should it it let out air before the fuel goes down to the pump? The mechanic from Alice Springs LR who helped me when I had broken down on the Great Central Road said the problem sounded like air going into the injector pump which makes it shut off allowing the air to go back up the line, then when the injector pump comes in again it drags the air back in - and so on. It sounds logical.
Bill

Pretty strange that you have no warning light, however I can not see a fault for low fuel rail pressure in the manual. Sounds like the vibration from the corroguations is causing one of the quick connect fittings to move and let air in, (I'm not to sure what the green plastic cover is for, possibly a fitting for attaching a vac gauge??). Sounds like a vacuum leak down test on the fuel supply system needs to be done to try and find the leak. Of course it could be something obscure like the throttle pedal sensor.....

If the vehicle is still under warranty I'd suggest getting LR to sort it out, you don't want to be in a position where LR can say "you've been fooling around with it, it's your fault". They also have the test gear to see if there are any faults logged in the ECU which can point them in the right direction.

Best of luck!

Tim

Edit: The fitting is a bleed valve, from the manual:

BLEED VALVE
The bleed valve is located in the fuel feed line near to the injector pump. It facilitates the use of a vacuum connection
to prime the fuel system and remove air during initial and service primes. This protects the injector pump from air
locking.

[Billj18]

Thanks again Tim.
It is under warranty. I have it booked in with LR at Barbagallos next Monday and will leave it with them for as long as it takes.
I will let you know how I go.
Regards,
Bill

[Hand clutch]

The word "rhythmic" caught my eye. That describes a problem I have encountered with my Puma three or four times. The symptoms are different and nowhere near as severe, but certainly rhythmic. It happens when I am heading up Gap Hill on the Calder Highway out of Melbourne. It's a long, straight climb and the Puma will normally hold 100 - 110 clicks all the way up in top. But on occasions, as I feed in a bit more accelerator to keep it moving towards the top of the climb, I get a very rhythmic 'vibration' through the vehicle. Vibration is probably not the best description but is the closest one I can think of. There doesn't seem to be a power loss. If there is, it is very mild. The solution is just to back off the accelerator slightly. It immediately disappears, but pressing down again on the accelerator brings it back. The movement required to switch on and off is very subtle. I don't believe the problem is there all the time because I travel this road frequently and only experience these symptoms occasionally. Melbourne LR recently applied a software upgrade after it went into limp home mode for a few kilometres before restoring normal operation. The upgrade seems to have fixed that problem (they said it was a known problem and software patches had been developed) and it also eliminated another problem of a strange but fleeting noise sometimes experienced during the initial change into sixth when cold. I suspect you may have a software problem and my experience with the sensitivity of the accelerator perhaps points to that area.

[Billj18]

Thanks handclutch. When I took the car to LR Albany they did a software upgrade and I still have the problem so I am not sure - maybe I have more than one thing happening. Certainly when I pressurised the tank and got all the air out, the problem went away - for a while. Hopefully Barbagallos will be able to sort it out next week. The problem is that you have to drive up a sustained grade or at high speed under load for some time to get the symptom and Perth is flat so they may think thay have fixed it when they haven't. Anyway, I will persist.
Thanks again.
Bill

[Billj18]

To Tim NZ.
Tim,
You mentioned a "manual". I have been unable to get hold of the new common rail manual so I have been making do with a TD5 manual. OK for everything but the engine and gearbox.... Can you let me know where you got yours.
Thanks.
Bill

[LR D4]

Hi Bill

Is yours the stornaway 130 with ZU rims I've seen in margs,if so very nice mate, sorry to hear about the issues, just follow this link to the digital copy of the puma manual... Defender2 - View topic - Last version in English!!! (http://www.defender2.net/forum/topic3553.html?highlight=manual)
Regards

LR09WA

[Hand clutch]

Bill, my comments might have been a bit ambiguous - the software upgrade didn't fix the rhythmic problem, just the very occasional regression into limp home mode and the strange noise when changing gears. Limited fuel flow would account for my experience, when I think about it. The problem only occurs when asking a lot of it. Back off the power a fraction and it can still get enough juice. Mine is a 110 cab chassis. It's led a fairly sheltered life - pushing it up Gap Hill would be as hard as it has worked. Suspect I would have the same problem towing a big load, but yet to find out. There is a hose that runs from the fuel filler back to the top of the tank. Not sure what it does, but I shortened both it and the main filler pipe to clear the rail under the tray. That had the effect of lowering it but shouldn't be a problem on an off-road vehicle designed to work at all angles.

[Billj18]

Thanks again. The line to the top of the tank is the return fuel line - my understanding is that fuel runs through the common rail under very high pressure and what is not injected into the cylinders is returned to the tank through the return fuel line that runs parallel to the delivery line. Essentially the fuel runs in a continuous flow through the lines between the tank and the engine and back again (I think). I expect your vehicle would not have the problem that mine had - I actually broke down half way between Laverton and Warburton on the Great Central Road and through my lack of understanding of the common rail technology was stuck for two days and nights. I had been led to believe that you didn't have to bleed a common rail motor. Only when I purged the air from the system through pressurising the tank did I get going again. A truck driver who stopped to help us suggested this but I was wary at the time and didn't do it. Only when I had been towed 90km back to a roadhouse and talked to Alice Springs LR (great contact) did I do it and get underway again.
Bill

[Billj18]

Thanks LR09WA. Mine is white 130 with white steel rims. The other one was a steel grey with alloy rimes - he has gone off somewhere. Thanks for the link to the manual. Are you in Maragret River?
Bill

[TimNZ]

Hi Bill, did you manage to get your vehicle sorted?

Cheers,