Pump Wiring Botchery!

[evilally]

Hello again! I'm back, this time with a lovely 406 purchased for the princely sum of £265. Needless to say it's needed a bit of work. The latest problem is that I'm investigating a running issue that I think is timing related. Whilst in about the fuel pump I noticed this hiding under some insulating tape:






...there are 3 wires going into the sheeth, but 2 have been snipped off. What is the sensor (arrowed)? Would this affect pump timing? If I remember rightly there are certain persons on this forum who are expert in the field of Bosch injection pumps......

[CitroJim]

Welcome back Ally Good to see you again!

Just on the basis of the pictures and the fact the wiring is in the vicinity of the stop solenoid which I see is visible meaning the pump has been de-armoured and the immobiliser removed, I'd say that cut wiring was not the problem. It's been cut around to find and supply an ignition switched feed for the stop solenoid - the item you have arrowed.

The stop solenoid will have no effect on timing whatsoever. Why do you suspect a timing fault and what's the symptoms?

[evilally]

Cheers Jim

I'm still troubleshooting this, but the car runs and starts ok from cold, but as it gets warmer it runs progressively worse. When hot it hunts/misses badly on idle and can be difficult to start, it's also smoky. Another strange quirk is that when hot, it’s difficult to get the engine to rev to anything under 1,800 rpm. Pushing the accelerator pedal results in nothing…..nothing…..1,800rpm. It makes the car very easy to stall.

I should mention that I have rotated the LDA to its most aggressive to give the old girl a bit more poke. However when I did this, the pin that the LDA actuates got stuck. To free it, I had to remove the throttle arm to get access. Stupidly, I did not mark the position of the arm on the spline. I turned the throttle shaft until the engine was at normal idle, and refitted the arm. This was before this problem became apparent, but I honestly can’t remember if it was at the same time.

So far I have:

Replaced the ECU temp sensor.
Checked pins 4 and 21 with a multimeter, reading is fine.
Check needle lift with multimeter, 100 ohms.
Disconnected needle lift with engine running, engine stumbles slightly indicating the ECU is getting a reading.
Checked the rev counter works when needle lift disconnected, indicating crank sensor is fine.

Still to do:
Check out throttle arm potentiometer
Check for air ingress into fuel system (unlikely but I'll check it out anyway).

Interestingly I ran the car for a day with the ECU temperature sensor unplugged and there was no change whatsoever.

The car has run the last 24,000 miles on 1 micron WVO blended with 25% misfuel with cetane booster additive, however the problem is at least as bad on pump diesel (perhaps worse).


As in the past, any input would be greatfully received!

[evilally]

I got a little bit more testing done this weekend.

I bumped the throttle arm round one more spline on the shaft, but this resulted in the engine revving far too high. So I'm confident that it's in the correct place.

I checked out the potentiometer on top of the pump. The reading from the multimeter was 1k ohm to 2k ohm resistance from no to full arm travel with no dead spots. Taking the potentiometer off and moving it to min and max with the engine running makes no difference at all. Also unplugging it made no difference. Is that normal?

I disconnected the timing solendoid on the pump while the engine was running cold. It resulted in very clattery/naily running. I don't know if this is a useful piece of information or not

[spider]

It probably will run badly if you unplug the timing solenoid from the pump as it will then go to one extreme.

I don't have any figures for the needle sensor or throttle pot, although you have checked them and the pot provides some changes and the sensor is not open circuit.

Does the 'K' engine management light work ? , the bulb may of been removed if not.

The ECU temp sensor is mainly (I think, well mine is on the TUD5 which has an electronic advance pump) to advance it slightly when stone cold so it actually idles properly as they are devoid of a cold start cable affair.

A quick Lexia / PP session may well provide the clue. The ECU does not control the immobilizer on these, but you don't have one anymore anyway. The other wires that you noted are probably for what was the module around the pump (that has no effect on running)

[evilally]

Hi Spider, somehow I overlooked your reply. Yes, the K light works.

Tonight I bypassed the filter housing with a little in-line filter. The in-line filter is transparent so I can see the fuel flow. No air ingress to speak of, and it's made no difference. I'm not sure what's next, I won't have time to try anything else until next week anyway. Perhaps I'll stick some transparent hose on the return line to see if I'm getting air in at the pump.

[evilally]

After a long drive, the car refused to start today At a funeral of all places! Got it going with some WD40 in the inlet but would stall as soon as my foot was off the accelerator. Ran it for a few minutes then was able to get it home. It sat on the drive for an hour and a half and wouldn't start again. I unplugged the timing solenoid and it started reasonably easily, albeit it sounds like a tractor! Unplugged the idle speed is steady, plug it back in and it starts hunting badly.

Although the needle lift returned the correct multimeter reading, I still have my suspicions. When I unplugged it the first time around, the engine stumbled ever so slightly. Tonight, unplugging and reconnecting it a few times in a row sometimes had a small effect, other times not. Other discussions on this suggest there should be a more pronounced difference. I think I'm going to replace it anyway to eliminate it.

Any input on the above gratefully received!

[evilally]

Spent some of today completely draining the tank and refilled it with £60 of pump diesel. This has actually made things worse somehow, it won't start at all. I'm starting to suspect I'll be replacing an injection pump next week

[CitroJim]

Ally, that is odd. Right let's start from the beginning and apologies if I'm guilty of teaching you to suck eggs here...

First test is very easy and will confirm if fuel is reaching the engine. Crank it well and watch the exhaust. Do you see any smoke? If you see white smoke then this is unburned but atomised fuel so you then know the pump is delivering fuel and the problem is either a full set of faikled glowplugs or a problem with the glowplug controller. Remember an XUD must be preheated always and if the glowplugs are not good it'll never start.

Black smoke means it's trying but can't for some reason get running - often due to a big timing error (too retarded) or a major blockage in the air intake.

If that didn't work and you see no smoke at all, do you have fuel getting to the pump? Test by disconnecting the return line on the pump and pumping the primer. Fuel should issue. Then crank over and gain plenty of fuel should spill from the return line. If it doesn't then the engine will never start so that leads back to some problem with the fuel supply.

If that's OK, ensure you have 12v on the stop solenoid when the ignition is on. I say this because you know it's been bodged around there.

If that's good, then loosen one injector delivery pipe union and wrap the union in a rag. Crank over and if the pump is working then the rag will be damp with fuel. be very careful doing this and always use a thick rag as diesel under pressure can cut skin like a knife and it's not good for you.

If that's good then there's fuel reaching the injectors.

If not then the stop solenoid may be duff and this can be checked by removing it, removing the plunger and replacing it. It'll no longer work as a stop solenoid but will confirm if it's duff. Should the engine now fire up there is an emergency stop lever on the front of the pump.

A duff Needle Lift Sensor will not prevent a start but if there's an internal fault in the pump that's keeping it fully retarded then it'll be incredibly hard to start and you'll see black smoke.

lastly, if all this draws a blank, is the pump actually turning? Check the cambelt! I know it's obvious but it's been missed in the past and another thing to check if it's all very baffling and not making sense is to check the woodruff key is in place on the pump driveshaft sprocket - I've known them fly away when replacing a pump and for a time the friction on the shaft taper will hold the sprocket in the right place but over time it'll slip and this will upset the timing to the extent the engine will just not run and how yours has been gradually getting worse then this is a possibility although remote I must admit...

let us know how it goes! I think I’ve covered everything there...

[spider]

I don't have much to add. I thought about the pump too Jim, although not the woody key. I was thinking more along the lines of it breaking the driveshaft internally although (someone correct me if I'm wrong) so it appears to work but nothing actually happens inside. I think that's a Lucas 'feature' normally and I see a Bosch unit.

Having said that if there's fuel available with the unions slightly opened (note for future or those finding this with a search, only do this on an indirect injection engine, doing it on a HDi is quite / very dangerous!) then the pump is working.

Good point about the key though, I'd not of thought of that for ages.

[CitroJim]

The driveshaft shear is a Lucas feature Andy and can't happen in the same way on a Bosch. However, what can happen is the plunger springs can break and prevent the HP pumping element moving correctly and could even break it - it is made of very hard and therefore brittle steel. That can be tested by slipping off the cambelt and turning the pump by hand. If a Bosch turns over easily without four very strong 'compressions' being felt then it is not a happy thing inside at all..

In fact on a Bosch the only thing that can seize is the HP pumping element and it'll very soon break if it does.

Good call on NOT doing the test described with the injector unions on an HDi. It would be extremely dangerous.

I've thought of one other thing...

If everything else checks out then only possible thing left is lack of compression. It's a quirk of the XUD9 9 (and 7) that valve clearances are tightest when stone cold and the colder the tighter. Engines with marginal clearances will start when the weather is warm but not when it's really cold as the valves can be just held open and thus killing compression.

If all else checks OK then do slip off the cam cover and check the clearances with the engine very cold.

Ally, do let us know how you get on and I hope Andy and I have been of some help here...

[evilally]

Jim, Andy, many many thanks! I've got some stuff to work through, I'll report back asap. The snow has finally found us, I'll try to zip up my man suit and get out there!

[evilally]

Hi guys, I finally managed to recover the car from my parents. It would crank but no signs of life at all. White smoke evident. I got it fired with a can of Easy Start. Even when up to temperature there was a lot of white smoke:



Strong pungent waxy smell.

My old man followed me home. He confirms that under light load there is a lot of white smoke, but when pushed a bit harder it seems normal. The car has no shortage of power at all and pulls well when moving, this would suggest to me that there isn't a compression issue?

I think I can rule out plugs as it clearly has problems even at operating temperature.

The fuel pump is supplying fuel as we can see unburned fuel at the exhaust

The old boy thinks it's idling on 3. He has suggested an injector fault. An injector problem sounds plausible? I fancied a recon set anyway, so I think I'm going to whip them out and send them off.

In the meantime I might take the cam cover off and check the timing and pump pulley as suggested.

[spider]

It does smoke a bit. It sounds a bit rough too.

Injector or lack of compression possibly. If you can borrow a diesel compression tester that may help determine. Interesting you say it goes OK which sort of narrows it down from a compression concern.

Valve clearances ok ?

Coolant look ok ?

I wonder if the head is cracked. Although something at the back of my mind tells me to tell you to check the EGR valve is not stuck (slightly) open or something.

[evilally]

I'm trying to source a compression tester but as you say unlikely to be an issue as it pulls well. Coolant is clean, no gunk in oil cap. No significant blow back out from the oil filler either.

Interesting that you mention EGR.

I haven't a clue how to check clearances, but I'll read up on that. I'll need to take all the pipework off the top of the engine to get the injectors out anyway, might as well take a look.