Xantia hdi cut out , no power at fuel pump

[orosurf]

Hi everybody, been a while since I was here. Today I had the front bumper off to fit new fog-light bulbs. I did the job, put it all back together and feeling pleased with myself started the engine. It was running normally for about 5 minutes then suddenly stopped and wouldn't start again. I checked the recently fitted fuel pump and found it wasn't running, as it is a Chinese one, I tested it with a direct feed from the battery, all ok. I even started the engine like this. I checked the fuse and listened for the clicking of the relay, both seemed ok, relay clicks. I then used a bulb and wire to check the fuel pump connector for current, I couldn't find any (ignition on) . I then went to the under bonnet fusebox and used my bulb/wire tester to check the fuses for power. I found that fuses 9-15 have no power, all the others do. This is as far as my knowledge goes. I am stumped, how can the relay click if there is no power going through the relay fuse (number 9) ? Can anyone tell me what might be going on here? I am at a loss. Trying to avoid the cost of a tow truck. Car was running great until today. Would really appreciate any clues from more experienced members.

[myglaren]

I'm reasonably certain that the relay will click when it receives an activating signal but if the fuse is gone for the power supply then there will be no output.

[orosurf]

Fuse is apparently ok (fuse 9 under bonnet) I changed it anyway. There seems to be no power to any of the fuses 9, 10, 11, 12 13, 14 and 15. I don't understand how the relay can click when the number 9 fuse has no power ?

[Xantidote]

I had a quick look at the wiring diagrams in my Haynes manual, but couldn't see much of help.

As Steve (myglaren) has said, a relay will click when it receives an activating signal. I think in your case, on switching the ignition on, it is triggering the fuel pump relay (and a few other relays I expect). Modern relays generally have 4 terminals, and each "pair" are on separate circuits entirely, the triggering pair becoming live (in Steve's parlance, they are active) when you activate the ignition. This circuit then pulls the relay's internal contacts together, which is when you hear the click, and in doing so, makes the relay's other two terminals link together so that the heavy current can flow through the relay to the fuel pump. Purpose of relays is to avoid high current being passed through such as the ignition switch, headlamps switch etc. As you've said, there's no power to several fuses, so there's no power available for the relay to switch through to the fuel pump, and this is what you need to investigate. Might be useful to check what other circuits are/aren't working. Maybe one of the maxi fuses has blown.

It may be coincidence that this happened after you had the front bumper off, but there's a main wiring loom runs along the underside of the radiator, although I can't immediately understand how this could affect the fuel pump issue.

[Stickyfinger]

I
It may be coincidence that this happened after you had the front bumper off, but there's a main wiring loom runs along the underside of the radiator, although I can't immediately understand how this could affect the fuel pump issue.

[CitroJim]

It can Alasdair as that loom carries virtually everything, even the earth for the dashboard clock!!!

It has a number of splices (joints) in it that can fail... They can get damp into them, often from the cooling system, and that corrodes them.

[orosurf]

Thanks for all the replies guys. The garage got it going again, though I am not sure how. The fuel pump seams very noisy now though and runs all the time . Is it supposed to do that ? I don't recall it being this noisy before. I have a new problem now, the heater blower has stopped, bad news in Russia as we go into winter...

[CitroJim]

The pump should run all the time the engine is running but should not run all the time regardless... Just in case they've done a 'mod' to the wiring do this check:

Switch on the ignition following a fair rest but do not start the engine. The pump should run for about 3 or 4 seconds and then cut out. This is a priming run on ignition on to get the system ready for a start.

Now start up and the pump should start running again.

If the pump runs all the time, even with the engine not running the wiring has been bodged and this is dangerous as the pump is is so wired via the ECU that it will stop instantly when the engine stops. This is to prevent fuel being pumped uncontrollably in case of an accident for example...

The pump should not be unduly noisy and certainly not intrusively so. A very noisy pump is a sign of a potentially failing one...