306 HDi Fuel Pump Problem

pugxpert · Post by **pugxpert** » 07 Dec 2005, 13:30

get some one to turn ignition on for you and put your hand on relay for low pressure pump which is situated behind battery next to engine ecu 15 pin coloured brown or black,double relay,as igntion goes on you should feel relay go click after 6 seconds it should go click again this is priming low pressure fuel circuit by operating pump in tank if you cannot here or feel this relay click the engine ecu is not controlling relay or no power to relay,also has your car got an inertia switch under bonnet if this has tripped will cut feed to pump coloured black or red situated n/s/f next to eng ecu

get yourself a bulb and 2 bits of wire and put across terminals in connector plug under right rear seat for pump the 2 thicker wires(the smaller ones are for gauge) switch on ign see if bulb lights try seprate earth as well

pugxpert · Post by **pugxpert** » 07 Dec 2005, 13:42

check fuse 35 in under bonnet fuse box also check here with your bulb this is supply for low pressure pump

CICA · Post by **CICA** » 07 Dec 2005, 14:56

Hi PugXpert,

By the look of your last two posts you certainly didn't get that name for nothing!

Right well what I can tell you is that... Firstly I'm having to turn the ignition myself then run round to the bonnett to feel what I think is the correct location for the "click".

But I'm not sure if I am checking the correct place. There is what looks like a large plug under a black plastic cover behind the battery. It definately has more that 15 pins though and it also has a form of handle release and by lifting the handle the plug lifts off. I'm not entirely sure what this plug is. I've tried to be as precise as possible when describing it. Take a look at this image in the URL below and the same plug can be seen behind the battery with a black plastic cover over it. Is this the fuel pump relay or is it the ECU? (I can feel a click from this after about 6 seconds)

http://www.pug306.net/cpg132/albums/use ... 5B1%5D.jpg

Hopefully you will notice the small red dot in this image barely visible behind this plug. This is also present in my car and I assume this is the inertia switch which I have also tried pressing.

I have also check fuse 35 under the bonnett which appears to be ok as well...

(by the way this image is not of my car engine)

pugxpert · Post by **pugxpert** » 07 Dec 2005, 16:11

in your picture under that plastis cover is the engine ecu by your description i think this is what you are disconnecting right down the back a bit further is the double relay which controls engine ecu and other various things including the low pressure fuel pump,this is what should click after 6 seconds ecu swithes off low pressure pump through this relay,you really need to start checking for supply to the pump at fuse 35 and connector under back seat, you could try and get car to your local bosch agent they may be able to help or you are going to have to get a sparky in! but get a good one that knows the system otherwise he may start changing parts which will be costly to you

Post by **DHallworth** » 07 Dec 2005, 17:37

that red button hiding behind the ECU is the emergency fuel cut off switch.

In the event of an accident, the fuel supply to the engine is cut off. To restart the car again, you have to push that switch which i think basically resets the system and it starts to feed the engine with fuel again.

David.

CICA · Post by **CICA** » 07 Dec 2005, 18:21

Hi PugXpert,

OK I'll go and have a look at this relay again. Cheers for taking the time to provide such detailed replies

You're a credit to the forum!

(10 Minutes later)

I just nipped out to the car there again mate, and I located that relay. A small brown box like you said down behind the ECU. And it does click after 6 seconds, so I take it this means there is power coming to it? If so I am right in saying that this now isolates the problem to be between the double relay and the unit that plugs into the pump (and there is no problem with the ECU)?

Unfortunately I have no means of testing if there is power coming to fuse 35 under the bonnett and the unit under the rear seat that plugs into the top of the fuel pump has female adapters (as apposed to the male "stick out pin" type adapters) which makes it that bit harder to cross with wires and test.

Well I have the car booked into a garage for tomorrow morning and it looks as if it'll still have to go there but at least I can provide the guy with this information which in turn "should" mean he won't take as long at fixing the problem. Therefore a smaller bill!!

CICA · Post by **CICA** » 07 Dec 2005, 18:22

Cheers for that one David... I'll go and try resetting this switch.

wheeler · Post by **wheeler** » 07 Dec 2005, 19:48

CICA wrote:it does click after 6 seconds, so I take it this means there is power coming to it? If so I am right in saying that this now isolates the problem to be between the double relay and the unit that plugs into the pump (and there is no problem with the ECU)?

just because the relay is clicking only means the primary side (coil bit) is getting power,it doesent mean there is power going into or even out of the secondary side,the double relay usually has at least 2 main battery feeds going in (pins 8 &11) and it wouldnt be unusual to find a weak feed here.you need to check the feeds going in and out of this relay.use a test lamp to check the feeds rather than a multimeter (sometimes the meter can show 12v but there is not enough current to light a bulb)

pugxpert · Post by **pugxpert** » 07 Dec 2005, 20:35

spot on there wheeler,just what i was going to say next, if you bridge pins 4and 8 on double relay pump in tank should run

CICA · Post by **CICA** » 07 Dec 2005, 22:47

Thanks to the both of you guy's for the help with this... Much appreciated!!

CICA · Post by **CICA** » 09 Dec 2005, 17:30

Hi Guys

The Saga continues!!

I have had the car fixed and the auto electrician replaced the relay for £20 as the replacement came from a breakers yard so it wasn't too expensive to repair.

But on fixing that problem I have since noticed another problem and I was wondering if any of you guys could help. When I now go to start the car the iginition glow plug light on the dash board now longer lights up, but the car still starts alright? This light always came on even before I left it in the garage to get it fixed.

Firstly: Will the fact that this light is not coming on have any bad effect on the car?

Secondly: How would I go about looking to repair this problem? I assume this has arose from the auto electrician trying to fix the relay problem but I don't know where to start looking in order to try and fix it?

Can any of you guys please help?

wheeler · Post by **wheeler** » 09 Dec 2005, 19:18

CICA wrote:
Firstly: Will the fact that this light is not coming on have any bad effect on the car?

Secondly: How would I go about looking to repair this problem? I assume this has arose from the auto electrician trying to fix the relay problem but I don't know where to start looking in order to try and fix it?

Can any of you guys please help?

I wouldnt just assume it is due to the auto electrician,i cant think what he could have done to cause this problem.i would start by checking that the glowplugs are being fed.

CICA · Post by **CICA** » 09 Dec 2005, 22:50

Hi,

Don't know a lot about glow plugs but wouldn't these glow plugs have to be getting fed in order for the car to start? (as the car is starting again no problem)

If the glow plugs do not need fed in order for the car to start, I would probably be better checking them for feed. The only problem is I wouldn't be too sure how to do this and where to find the glow plugs

Post by **DHallworth** » 10 Dec 2005, 01:05

I also have an HDi 90 306.

And in the 14 months that i have owned it, i can honestly say i have never once seen the glow plug light on the dashboard light up, not even when i initially turn the ignition on.

Regards
David.

wheeler · Post by **wheeler** » 10 Dec 2005, 18:28

The HDi only needs to use glowplugs if it is REALLY cold. At 0 degrees C they only operate for a second.