Td5 Fuel Pump

**Mulgo** · 29th May 2009, 02:20 PM

Hello,

First I thought a fuse is gone - all good, then I thought about the fuel pump - but it is working fine.

Then I discovered that somehow I don't get power to the back of the Defender to the fuel pump.

If anybody is a master in reading those electrical diagrams - could you please confirm, that my assumption is correct: The purple-white cable from the black fuse box (under the drivers' seat) should carry +voltage to the fuel pump.

If that is the case - why do I have power at the beginning of this cable (at the fuse box) but not at the end (fuel pump)????

Thanks.

Cheers,
Daniel

**Psimpson7** · 29th May 2009, 02:25 PM

Yep Purple - White goes from the fuel pump relay to the fuel pump

**foz.in.oz** · 29th May 2009, 02:25 PM

The purple and white cable goes from the fuse to the fuel pump relay under the seat. This relay is controlled by the ecm. The white and purple wire from the relay goes to the pump. The relay should energise when igniton is turned on and the pump should run for about 30 seconds or so before turning off if the engine hasn't been started.

edit - The inertia switch interupts this circuit so make sure that it has been reset too.

**Mulgo** · 29th May 2009, 02:55 PM

Originally Posted by foz.in.oz

The purple and white cable goes from the fuse to the fuel pump relay under the seat. This relay is controlled by the ecm. The white and purple wire from the relay goes to the pump. The relay should energise when igniton is turned on and the pump should run for about 30 seconds or so before turning off if the engine hasn't been started.

edit - The inertia switch interupts this circuit so make sure that it has been reset too.

What is the 'inertia switch' and where is it located?

**Psimpson7** · 29th May 2009, 03:05 PM

Intertia switch goes off in accident to stop car. Is located on bulkhead under bonnet.

Its a small black square switch with a rubber cover.

can see it on the right of the header tank here:

**foz.in.oz** · 29th May 2009, 03:16 PM

PSimpson7, I couldn't have put it any better myself.

Just press down in the centre of the top surface to reset

**Mulgo** · 29th May 2009, 03:19 PM

Originally Posted by foz.in.oz

The purple and white cable goes from the fuse to the fuel pump relay under the seat. This relay is controlled by the ecm. The white and purple wire from the relay goes to the pump. The relay should energise when igniton is turned on and the pump should run for about 30 seconds or so before turning off if the engine hasn't been started.

edit - The inertia switch interupts this circuit so make sure that it has been reset too.

Checked the relays. This td5 (MY2001) has two relays under the driver seat: one yellow and the other black. There is no purple-white cable to either of those relays.

**foz.in.oz** · 29th May 2009, 03:43 PM

It might be with the fuses in front of the gearstick. I need to check a manual

**Psimpson7** · 29th May 2009, 03:46 PM

No, its one of the ones under the seat.... cant remember which one. Will go and have a look.

ETA Its the yellow one, and I dont have a White and Purple one either (mines also 01) so the wiring diagram may be wrong.

**Mulgo** · 29th May 2009, 05:26 PM

Ok, had a look through the Electrical Handbook on how that pump is supposed to get its power:

********************************
Current runs from the battery+ via a brown cable to the fuse #4 and to the fusible plug #5 in the black fuse box under the seat. The fusible plug #5 is connected to the ignition with a brown/white cable.

When the ignition is on position II current runs to fuse 5 (in front of gear stick) via a white cable. From this fuse the current runs via a white/green cable to the ECU.

From the ECU the current continues via a cable brown/orange and blue/purple to the fuel pump relay (the one furthest to the right in front of the gear stick). Blue/purple cable is also connected to the alarm system.

From the fuel pump relay the current continues via a purple/white cable to fuse #4 (under the drivers' seat). From there the current again via a purple/white cable to the pump.
***********************************

Having read all that and compared it with the problem I am facing - it means for me that there must be somewhere a bug in that purple white cable from fuse #4 to the pump!

Correct?

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