If your HDI cuts out or feels under powered

[Poodle]

This is a beginner’s guide, and is a work-in-progress, it is by no means definitive and I am not a professional. Any work undertaken on your car according to this guide is done so at your own risk. I have restricted information in this guide to that which relates directly to the fuel system only. As mentioned in Mooey’s post above, there are other factors that may cause similar symptoms (particularly non-starting), please give these alternative options due consideration before deciding to attack your fuel system. All that aside, this guide contains a lot of information I hope you will find useful. This information has mostly been gathered from my own personal experience and that of certain members of this forum. Particular thanks go to Pro_steve, Mooey65 and Jaymes306, also to a chap whose username I can’t quite remember (maybe Mike_T on .net…?) who first introduced me to the wonders of Lexia/PP2K diagnostic tools.

If I had to make just one recommendation from personal experience, it would be this: Do as much testing as possible before spending any money, you will only regret jumping to conclusions, as will your bank balance (unless you get lucky, and I mean really lucky).


Rule Number 1
As you will have probably discovered by working on your car for other purposes by now; never assume the last guy to work on the car knew how to do their job properly – check everything! If something is leaking, don’t jump straight to the conclusion “it must be broken”. Instead, assume the last guy was a moron and check it’s actually been done up/has had the right gasket fitted/is the right part/etc, could save you a lot of time and money in the long-run. Also, don’t fall victim to this yourself, use breaking fluid when taking apart, use correct torque settings when putting together, finish each job completely before moving  on to the next to ensure nothing gets missed or forgotten.

Rule Number 2
These systems are seriously picky, the slightest thing out of place can stop them working. To this end, keep everything immaculately clean; the tiniest bit of dirt in the fuel system on the high-pressure side can undo days of hard work, so go careful.

Rule Number 3:
When working on the fuel system, always buy genuine. Doesn’t matter whether this is Peugeot or Bosch, it’s all the same essentially, but don’t waste your time with pattern parts. This applies right down to service items such as the fuel filter. In fact, especially the fuel filter! It’s worth getting friendly with your local Bosch specialists as they will be well qualified to answer any complex questions and, in my experience, are usually happy to help. Might even get some discount…


Tools required:
A wide assortment of basic sockets, spanners, screwdrivers and the like is useful, but I’ve found the two most valuable tools to be:
1. Access to another car that runs fine, so you can swap bits over to try and find the item at fault.
2. Peugeot Planet 2000/Lexia diagnostic tool.
(I realise neither of the above are very accessible to many people, but I’d recommend you beg, borrow or steal your way to having at least one of the two, preferably the PP2K. There are a few members on the forum, myself included, who have these tools already and may be willing to help.)

You will also need:
3. A whole lot of patience. There’s a lot to the fuel systems on these common rail cars and it’s not usually easy to find the fault, so don’t give up easily.

The rest I will put at the top of each item’s section, as there’s a lot and some of it is quite specific.

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CONTENTS:

1. Leaks

2. Low Pressure Components
2a) Lift pump
2b) Fuel filter housing

3. Electrical Components
3a) Brown relay
3b) FRPS (Fuel rail pressure sensor)
3c) ECU (Engine control unit)
3d) FPR (Fuel pressure regulator)
3e) Third piston shut-off
3f) Fuel temperature sensor
3g) Other connections

4. High Pressure Components
4a) High pressure pump
4b) Injectors
4c) Fuel rail

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*1*

LEAKS:

Firstly, look around the engine bay and fuel system, check for signs of perished hoses, worn fittings, etc. You may find you have obvious signs of a leak - a wet streak down the side of your fuel filter housing or a pool of diesel around one injector, for example. If you find anything, check it is actually diesel (a bit on the end of a finger to sniff - giggidy - should tell you), clean and dry the area carefully and check again after a few (100-200) miles. If the wet patch has reappeared and is definitely diesel, then you shouldn’t have to look far to find your leak.

Prime suspects for leaks:
1. Injector hard-pipe unions
2. Injector leak-off pipes
3. Fuel feed/return pipe unions
4. Fuel filter housing, particularly the lid and drain screw
5. Fuel tank filler elbow/breather hoses

On finding fault with any of the above, as mentioned already, check that the item is properly fitted before paying out to replace it.

It is possible, although unlikely, that your high pressure pump is leaking from one of the fuel controls – the FPR or third piston shut-off solenoid - or one of the fuel lines connected to the HP pump.

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*2*

LOW PRESSURE COMPONENTS

Lift pump



Tools:
Large flat-headed screwdriver
Hammer

The lift pump is under the osr passenger seat, lift the cut out in the carpet and the plastic cover to access. When you switch on the ignition this unit should run for a few seconds to prime the system. Signs of failure are:
Intermittent running.
“Gold” filings in the bottom of the fuel filter housing.

It is worth checking the electrical connections and that the lift pump is receiving the correct signal (6 volts I think, anyone able to confirm?) A poor or absent signal points to the brown relay, covered under “Electrical Components”. Unplug the lift pump from the loom. Use the hammer and screwdriver to tap the plastic securing ring in an anti-clockwise direction to loosen, finish undoing by hand and remove. Surround the hole in the chassis with a sheet of plastic to avoid dropping diesel all over your interior, the lift pump can now be lifted out of the tank. Check the external filters for any muck.

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Fuel filter housing



Tools:
22mm 6-point socket
1m length of fuel hose
Container for fuel

The fuel filter housing is in the front of the engine bay near the centre with 5/6 fuel lines going to/from it. You should be able to hear any air-leaks on this, they will usually make a keening noise; leaking fuel will be visible. There are numerous unions that may leak, as well as the lid or drain screw.

Cover anything below with plastic sheeting to protect it from the spilt fuel, a couple of rags directly underneath should stop the fuel spreading if spilt. Drain the filter housing by the drain screw at the base, connect the hose to the tap and drop fuel into the container. Disconnect the two fuel lines to the lid of the filter housing, plug both sides of the unions immediately to stop dirt getting in. Use the socket and bar to undo the lid, apply pressure progressively and evenly as it’s quite easy to damage the plastic hex. It will unscrew about 90 degrees then lift off, be careful not to lose the spring washer beneath. The fuel filter can just be lifted out, it should be clean and a genuine Bosch. The sealing surfaces on the lid and filter housing should be clean and smooth. There is a sprung ball-bearing type valve in the bottom of the lid, this should be clean and smooth. Remove the drain screw completely to check the condition of the o-ring. The whole housing can be removed by pressing in the tab behind the housing; this can be accessed via a cut-out in the bracket.

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*3*

ELECTRICAL COMPONENTS

A multimeter, small screwdriver (to release clips/tabs) and some contact cleaner are useful for most, if not all of the following components.


Brown relay




Tools:
Mirror
Light
10mm socket/spanner

This relay is behind the ECU and quite awkward to access. It controls items such as the lift pump, FPR and fuel heater and can cause intermittent running issues.

Unfasten the relay from its bracket, you may find a mirror and light helpful to see what you’re doing. Unplug it and examine both the plug and socket for signs of a poor connection - dirt, corrosion, signs of arcing, etc.

Note: Signs of failure may not be visible on the exterior of the relay, it is not an expensive part, so if in doubt I would replace it to be sure before paying out on more expensive options.

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FRPS (Fuel Rail Pressure Sensor)



Tools:
27mm spanner

This sensor is screwed into the underneath of the fuel rail with a red plug going to it. A broken FRPS can stop the car from starting or can cause cutting out (ECU shuts off engine when readings go outside of accepted parameters).

Test the signals emitted with a multimeter, you should see about 1.3v at cranking.

Unplug and unscrew from the fuel rail, it will spill fuel, so take precautions as described previously.

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ECU [& immobiliser]



Tools:
10mm socket
EOBD reader

The ECU is situated near the ns base of the windscreen, just behind the battery. It can cause non-starting.

Note : The ECU can be damaged in a number of ways or prevent starting due to other faults, often with the immobiliser.

First check your loom plug and ECU socket for signs of poor connection, arcing or bent pins. If those points are clear, then the only way to really test this is with PP2000. Limited or no connectivity or nonsensical data points to software corruption, you will need to send the ECU off to a specialist to be inspected and, if necessary, repaired. I would recommend testing all alternative options if possible before having the ECU looked at; it is rarely a problem.

First disconnect the battery. Release the clip and remove the loom plug. Undo the 3/4 10mm nuts holding the ECU to it’s supporting bracket and slide it forwards off the studs.

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FPR (Fuel Pressure Regulator)




Tools:
T-30 torx
Multimeter

The FPR is mounted to the gearbox side of the HP pump, facing the fuel filter housing. This can cause running on, poor running, non-starting and cutting out under load.

You can test the signal going to the FPR with a multimeter. (Readings unknown, research continues.) Check for signs of a poor connection in the plug and socket. You can also clean the FPR by flushing it out with WD40, carb cleaner, plusgas, or similar, you should remove the o-rings first to prevent them being damaged by the chemicals.

Undo the two torx-head bolts

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Third Piston Shut-off



Tools:
T-10/15 (confirmation?) torx

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Fuel Temperature Sensor



Tools:
19mm spanner

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Other connections

Yellow plug

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*4*

HIGH PRESSURE COMPONENTS


HP Pump



Tools:
This is a cambelt off job, so you will need a good range of basic tools, but there are no specialist tools required



Any testing of the HP pump requires high-spec flow benches and similar tools only likely to be held by a diesel specialist. If you wish to disassemble the pump yourself regardless, then take a look at my thread here for more details.

Injectors



Tools:
13mm & 14mm open-ended/crows-foot spanner
13mm socket

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Fuel Rail



Tools:
17mm & 19mm open-ended/crows-foot spanner
13mm socket/spanner

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If anyone has any ideas for additions to this guide, suggestions for further expansion or mistakes you have spotted, please do drop me a pm and I’ll sort it out. Same goes for questions, I’m always happy to offer help and advice where I can.