need wiring help!

I've converted my mk2 golf to digifant 8v, using a pre 90spec donor car. I've fitted everything I needed from the donor, all running gear, fuel pumps, wiring looms, clocks, MFA stalks, the lot. But the fuel pump won't prime when the ignition is turned on, it turns over OK, and the ignition stays on when its turned off. I've had a mate with a digifant gti come down today so I can check all my relays and wiring is connected correctly. I did have some things plugged in wrong, which I've rectified. There is also a really long cable that goes from the coolant tank side of the bulkhead to the airbox side with a plug thats identical to the coolant bottle and brake fluid resevoir plugs, with a brown and red/white wire. No idea where it goes and I couldn't find it on a mates gti. Any ideas?

Well i would say consult a wiring diagram for this as there is many options.
But basic checks would be:

Check fuel pump relay is recieving power on ignition
Check wires on back of barrel are correct if the ignition stays on seems its not recognising the off position(ALso check earths are ok)

ill ask about also see if i can come up with some more.

I will have a wiring diagram soon for one of these so will post it when i get it.

Its OK, I had an auto electrician come out to it, seemed the ECU was duff. I went and got another one, which seems to be as bad as the other one! I've taken the original one apart and found this....



Just been and bought a good soldering kit, so I'm gonna repair it and hope it works!