C5 HDi In Tank Fuel Pump Power Supply Problem?

[sinkz]

I have a 2004 2.0 HDi C5
Never had any problem starting in cold or rain or shine.
Recent problem with difficult starting so I changed the glow plugs with no real effect.
Problem seemed to have settled down or 'cured itself' and ran car for a few days with no problems.
Driving home a few nights ago the engine cut out completely. Couldn't get it to restart and had to call AA to get me home. AA guy pulled off fuel line to filter and no fuel was coming through.
Next day checked fuel lift pump but couldn't hear it running at all. I removed in tank fuel pump and connected to a battery outwith car. Pump runs seemingly ok.
Checked power supply to pump as with pump out of car I could work out/see which wire on multi plug was supply.
I seem to be getting approx 3.0 volts when ignition is switched on which then drops to about 2.1 volts after a few seconds.
I do not have a wiring diagram. Can anyone help with suggestions as to fixing problem?
Is there a relay somewhere which may be faulty? Checked fuse from detail in Haynes Manual but it seems ok. Considering running another fused supply to pump to check if it will run and start car.
Suggestions and advice would be greatly appreciated.
Thanks
Merry Christmas and Happy New Year!

[Peter.N.]

As you say a circuit diagram is needed but with the complications of modern car electrics the easiest solution might be to run a seperate feed from an ignition switched circuit - unless someone comes up with a quick fix.

Peter

[sinkz]

Just a short update:

Managed to run a temporary separate power supply to pump which means that pump runs when ignition on. This allows engine to start!

Will try to find source of problem and re-instate proper wiring asap.

Again, any suggestions or a copy of a wiring diagram would be most helpful.

Thanks