Why won’t it start!?

[Mango Madness]

Evening, hope you’re all well. 
 

Anybody heard of this scenario?
 

BMN 170 won’t start despite there being literally nothing wrong with it. 
 

0 faults found after several scans.
 

No power to the tank pump when installed in the car. Been tested and works as it should on the bench. 

Everything electrical related to the fuel system has been checked. No wiring breaks, no sensor failures, everything is communicating as it should. 
 

Well and truly stumped. Any ideas? 
Thanks
 

[cliffcoggin]

14 hours ago, Mango Madness said:

BMN 170 won’t start despite there being literally nothing wrong with it. 

Tom. That's logical nonsense. If there is nothing wrong with the car it must start, therefore there must be something wrong.

Diagnosing unexplained electrical faults should always start with the battery. Without a decent battery no amount of testing will get you anywhere, so please tell us how old the battery is. Bear in mind that a dying battery may be able to crank the engine, yet be unable to supply stable enough power for the car's electronics to work.

[Steve Q]

Could there be an imobiliser issue? Are any of the carpets wet which could hint at damaged CCM. 

[Mango Madness]

Thanks for the replies folks. 

I’ve been resurrecting VAG cars for 30 years and never seen anything like this. 

First thought was battery, Cliff, as it looked like it’d been there since WW2, brand new one installed. 

Carpets are dry and there’s no indication of ever having water ingress.
Scanned with Vagcom/Rosstech and at an Audi dealership 
I’ve multimetered every wire l could find and there’s no continuity issues. 
Fuses changed just in case, as we used to say, “gone dry”, new relay fitted too while l was there. 

Here’s something new that’s literally just popped up for the first time. EPC Fault - See owners manual. 
 

Im now wondering if it is an ECU fault as Steve says. 
Thank goodness l kept the old Golf 4 PD130 just in case of emergencies. Hasn’t broken once since l bought it new in 2003.. 

[cliffcoggin]

An internet search for "EPC fault" showed me several possibilities that would be worth investigating, though I must add that I have no direct experience of it myself.

[Mango Madness]

Im not worried about the EPC fault indication, I’m more interested in the fact it wasn’t there previously during the multiple scans. 
You don’t always need specific experience to help, all cars work in essentially the same way. 
Any thoughts are always appreciated.

[Mango Madness]

We got there in the end, turns out it was the ECU. Despite scanning okay on the car it failed bench tests, weird.
Put an immo free test brain in it and it fired up straight away. 

Thanks to everyone that chipped in 👍