Fuelpump relais BX14

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pierre_verbakel
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Fuelpump relais BX14

Post by pierre_verbakel »

My BX stopped just underway. Found out that the fuelpump is not running. Under the backseat, I found it and decoupled the connector. Found out that it does run with battery directly connected. I suppose that there is some relais controling it.
Question: Which is the relais, and where can I find it. Is it one of the three blocks on the fuse-tray?
Any help very much apreciated.
Pierre Verbakel
The Netherlands
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AndersDK
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Post by AndersDK »

Hi Pierre -
Th BX14 fuel pump relay is NOT contained in the fusebox.
It's located somewhere in the engine bay.
I need a bit more info on your BX14 :
1) modelyear ?
2) make and type of engine management (ECU) fitted ?
The relay would have 4 connections :
2 thin gauge green wires for the coil
1 heavy gauge blue wire from +12V battery feed
1 heavy gauge yellow wire for feeding pump, injector, Lambda heater
pierre_verbakel
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Post by pierre_verbakel »

Thanks for the exclusion of the fuse-tray.
Model is BX14 TE, Modelyear 1991
Enginetype KDY
ECU is, I believe, a Bosch. It is mounted on the Distributor.
What do you mean by 'the coil'?
I saw two thick blue wires leaving the pump going under the tapistry, did not find out where they come out again.
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AndersDK
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Post by AndersDK »

Hi Pierre -
The coil is the relay's electromagnet, which moves the relay contact points inside the relay.
Your ECU will not be located on the distributor. The device found on the distributor is the ignition module.
The idea is to find any relays in the engine bay - then note the colour & thicness (gauge) of the wires routed to the relay.
The relay which exactly have the wire colours mentioned in my first posting, would be your fuel pump relay.
My best guess is that this relay is located near the battery on a BX14.
pierre_verbakel
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Post by pierre_verbakel »

I have found the relay, it was near the rightfront suspension-sphere.
I opened the relay and visualy and with a battery checked its operation. The contacts click and indeed the resistance is 0 Ohms, using a Multimeter. I remember the fuelpump to be in operation for a few seconds just as you switch the key to the restposition for normal operation, so just before starting. So I figured that the green wires connected to the relay should give me 12 volts for a few seconds. It appears to be that it does not give anything on my Multimeter.
So I suppose the fault is either in the wiring from the ECU (Yes I found it to be fixed under the passengerseat!) to the relay or in the ECU. I hate to think that the ECU has been blown up, since I suppose these are very expensive.
According to http://www.atal.cz/cars_system/car_systems_cd2.htm the KDY engine the ECU is a Mono Jet. A2.2. It is a box made of plastic (not ALU like in my BX16). To remove it seems to be quite a job, since I suppose that I have to remove the front seat.
What is the drawback of changing the wiring that relay is switched on based on a wire directly from the contact-switch? It would be a solution wouldn't it. Any experience with that?
I hope to hear back from you or other soon, since my wife is nagging me when I have got it running again ;-)
Pierre
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AndersDK
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Post by AndersDK »

Pierre -
Before doing any elaborate work or investing in costly parts - then simply try replace this relay !
They are known to be unreliable after many years in service. Despite you can test it works.
Also replace the spade connectors on the wiring to the relay, ensuring it's not corrosion that's fooling you.
What happens if you shortcircuit the 2 heavy wires from the relay ?
- can you then get the engine running ?
pierre_verbakel
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Post by pierre_verbakel »

Hello Andy,
The relay looked really nice on the inside. Connecting the two wires makes the pump work even with keyswitch in off-position.... So discarded that option. Also it did not start at all while doing that.
To make a long story short: I have been able to solve the problem. I found that the copper flatcable from the engine to the battery-clamp was broken loose. The hole in it ripped open. I suspect that therefor the readings of the MCU were faulty and would fail to let the engine run. When I held the loose end of the copper flatcable to the chassis, I heard the relay click and the pump to run. After making a nice new hole in the flatcable I connected it. Needed some time to get the engine running again. I had the cap of the carburator/airfilter, put it on again and the engine ran than finally. (Pfff). Initialy it drove strange when releasing the gaspedal. After putting it to a stop, switching off the engine and restarting it again this problem was no more their. I suppose the MCU was in a default setting and afterwards on a better setting.
I drove like a 10 km with it giving it full throttle here and then, and I believe it is all OK.
I am really amazed that the flatcable is connected to a bolt that has a double function. Holding the battery in place and connecting the engine-mass to the chassis. Very bad design Mr. Citroen!
Thanks for your support and I hope that this case might serve to some other misfortunate BX-drivers.
Pierre Verbakel
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AndersDK
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Post by AndersDK »

Then you simply have a problem with the earth from battery to chassis [:D]
This is found behind/downwards to battery.
No bad Citroen design - but simple service issues [8D]
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Post by JamesQB »

Good reason to always check voltages with the multimeter negative (black) test probe connected directly to the battery negative terminal to stop it seeming that voltages aren't present when they actually are.
Of course, one idea would be to always check that negative wires such as the one going to the relay are reading short to the battery negative terminal, any open-circuits caused by earthing straps being broken would show up then.
pierre_verbakel
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Post by pierre_verbakel »

Hello All,
I am afraid the problem is still not solved. Just tried the car again, after 2 hours of not using it and it started with some difficulty. Then it stopped after 700 metres driving! :(
So now I am puzzled. Adding it all up I now suspect one of the temperature sensors being bad. The last month it was difficult to get it running in the cold dutch mornings. The exhaustpipe is has a lot of black carbon at the end, indicating that the ignition setup is not ideal.
Today was a very nice day with a lot of sun. I started the engine at 18.30h when it was quite cold again (+3C). Could it be that some sensor is not operating well?
Please feed me with some new ideas and knowledge!
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Post by AndersDK »

Pierre -
You are messing around - with no clear goals.
Also you ask and gets advice - but then finds a bad earth strap and thinks that's the problem.
How do you think we may help ?
- of course the fuel pump is running constantly, if you shortcircuit the relay contacts (heavy wires). But this is meant as a test to see if the car now runs without problems, not as a permanent solution.
You need to find some kind of a track to the problem, if you don't want messing around for ages.
pierre_verbakel
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Post by pierre_verbakel »

Please let me say that I very much appreciate your and everyones input. I have always maintained my cars, but it is not an everyday activity. Only in case of problems I go into my overall-clothing and get my hands dirty. After 6 BX's, which were all different I always get into new surprises and experiences. I thought this board was to put it on the table in order to share views and knowledge.
I went from finding out that the fuelpump is not running to that the relay does not get current to get it switch to make the pump run. Since I understand that the two wires controling the relay run to the MCU, the MCU has decided that the wires should not have current, or that these wires are faulty with an internal break (I suppose unlikely since they are quite static unde the carpet, although I have read somewhere that people have been jumping on the passenger floor hitting the wiring to get the pump going again). The logic of the is steered by inputs and the software built in. When I suppose that the software is still OK I suspect that it is either the inputs given by sensors. Since the engine wasn't starting very well, which it did a few months ago with cold weather, the current behaviour might be an extension of that partially analog type of fault. I know that the MCU's can be read using some Citroen diagnostic equipment which can give some clue, although not to much. But I do not have this equipment.
What my plan is now to double check the voltage on the wires to the relay. Also I am going to check some sensors, if I can. I have to find some data on this. My Haynes does not cover the KDY engine. If that fails I am going to pay a visit the Citroen garage, donate a lot of money the manager for mechanic who does also not understand the problem. My experiences with garages have been mostly negative, despite all the diagnostic equipmen they have.
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Post by AndersDK »

Okay Pierre - fully understand your frustrations [8)]
Sorry my harsh words [:(]
1) Haynes only mentions the basic K1G engine type - not the monopoint injection KDY version.
2) You may find help on getting the ECU fault codes read out here :
http://www.tramontana.co.hu/citroen/fuel/test.html
Note that the fault codes are international standard, applies to all types of ECU's.
3) The ECU does not have sensors locking out the pump relay, instead you may have a fault (corrosion) in the wiring from ECU to this relay.
4) I am still very interested to have you replace the fuel pump relay - no matter what you have tried and measured on this relay. Relays do not last forever - and they do make weird things when they gets old.
You can "borrow" one of the relays from your fusebox. From left to right you have these relays in the fuse box :
a) engine cooling fan
b) rear electric windows (if fitted on your BX)
c) blinkers relay
d) wiper timer relay
e) front electric windows (if fitted on your BX)
f) rear window demister heater
One of relays b,e,f may be borrowed.
5) If the engine starts and then runs fine with this relay shortcircuited on contact set - then you KNOW that basically everything is working. It's just the relay that is NOT activated for some odd reason.
6) The fuel pump relay is a standard relay - as the ones commonly used for extra lights, horns etc.
Available from any shop that sells car equipment - at some 5-10 euro.
Please at least try - and then report back with any results.
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Post by pierre_verbakel »

The problem has been definetely solved. The problem was in the connector with +/- 8 wires, mounted on the engine. The motor-to-chassis flatcoppercable seemed to be the cause first since the relay clicked when I connected it. What actually must have happened then is that I touched with my hand the cableset in the tube just near to it. I found out that moving this cableset made the starterrelay click off and on. I found out that the connectors that are mounted on the motor put under a plastic cover was oxidized. On the BX14 KDY -engine this is under the airfilter. The special grease in the connector was all green due to copper oxide. I cleaned it with brushes and some painting chemicals (In dutch `Wasbenzine`). And put it together again. The engine did start immediately and is now running for more than a week without a problem.
I hope that the french engineer who came up with the idea to put connectors in plastic covers is now retired. It is absolutely crazy to do this since it only keeps moisture for a prolonged time under the cover. All the other connectors used for the sensors are much better quality with rubber covers. I suppose that some of the sensors go through these wires. Most measurement is based on resistance measurement. Therefor if somebody has some time to spare it would be good to check this connector.
Pierre Verbakel
The Netherlands
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