From Super happy to Super Frustrated. Fuel Pump Issues

It's me again.
2001 Defender TD5

I lost power to the Fuel Pump and have done the following:

1. Replaced the relay - Twice
2. reset and even bridged the Nersa switch.
3. even replaced all relays under the driver's seat, just in case.

I can hear the relay kick in when I turn the power on and I can even hear the relay kick in and out when I prime the the Landy but the fuel pump does not turn on.
I have run a positive and negative to the pump directly and the pump turns on fine.
If I remove the relay and bridge the wires then the pump turns on.
Common sense says "relay" but I have tested and replaced it numerous times.
On the voltage tester it tests 11V

The previous time I posted on this forum I got help with something that frustrated me for months and yet the solution was so easy it was actually ridiculous.
Hoping someone can give me another ridiculous solution because I don't know where to look anymore.

Thank you in advance

Might sounds crazy but buy another relay and try that.

If that works then you’re buying some bad batches of relays for sure.

Other than that only thing I can thing of is the ECU

have you checked the relay base for good contacts as they us captured spade connectors and the contact area is very small and they have a tendency of being pushed back in the holder .the relay you have are they a well known manufacture and check to see if they are diode or resistor types

The wiring looms on TD5s deteriorate. The metal composition in the wires is rather stiff and brittle and the insulation can break up too. Especially where they're housed in those corrugated plastic tubes that Land Rover used to 'protect' them. So there may be a wiring loom fault. If you don't have an electrical manual to hand, there are a lot of useful wiring diagrams on the LR Workshop site - for example https://www.lrworkshop.com/wiring-diagram/defender-2002-td5-300tdi-rhd/fuel-pump/td5

It's an obvious one (but maybe worth mentioning) - are you using relays with the right pin configuration? They differ in terms of which pins operate the internal switch and which ones carry the load to the component. The bog standard ones off the shelf in Halfords are different to the one needed to operate the fuel pump, as I discovered from the diagrams embossed on the sides.

mystery said:

have you checked the relay base for good contacts as they us captured spade connectors and the contact area is very small and they have a tendency of being pushed back in the holder .the relay you are a well known manufacture and check to see if they are diode or resistor types

Click to expand...

I had a "well known" relay break after a few days this week