Converted 2.1/4 to 300tdi fuel issue

Well I'm slightly stumped, I recently bought a 1984 90 with a 300tdi lump in it. It recently decided it didn't like to stop the engine once the ignition was switched off, usually just needed a little tap on the injector pump to fix. Changed the solenoid and the problem still there, if I disconnect the white wire going to the fuel solenoid the engine will switch off. With the ignition off and engine running I'm getting around 1.5-2v at the solenoid (guessing just enough to hold it in) I diconnected the cabling off the back of the ignition barrel and the engine still ran (didn't remove main 12v cable to ignition) my question is that where else would they of gotten a 12v supply to engage on position one of the key?? Is there a relay used somewhere and would it be deemed acceptable to rob a 12v feed from the likes of the fuel gauge sender unit etc as a fix rather than strip.the dash apart

Run a new cable, that's easy enough.

From the ignition or from the easier run fuel sender unit?

Brendan1213 said:

From the ignition or from the easier run fuel sender unit?

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Simple job no need to strip the dash, run a new wire from the pump solenoid to the ignition switched live.

thought i would just strip the top section of dash, only took 20 minutes. As i thought it looks like a blind person with a case of the shakes put most of it together, have never seen 6 cables joined together with a couple ounces of solder but thats done by the manufacturer apparently :-(, i reckon this was the conversion for switched live to the various parts in the engine bay,never seen that many bullet/spade connectors in one place.
getting continuity to earth from the switched live so the digging continues

You may find a couple of wires that have melted together, so it's a good idea to find it before you get more serious trouble.

Yes found the ofending wire, must of just been squashed against the bulkhead and earthing out. Will teplace the wire tomorrow along with the ignition switch since that decided to pop off during the investiagtion works

Ok no replacing the wires didn't fix the problem :-(
An hour later I found that the only other bridge from the 6 white wires is a brown/yellow with a voltage regulator from the ignition warning lights. Disconnected the multi plug at the back of the warning lights and engine now starts and stops when should..... disconnect battery warning light bulb and I get all warning lights to work and engine start stop when should (this was allowing 1.5v through the bulb and into the joined white harness giving enough voltage to hold open the fuel solenoid). Getting 13.5v at the warning lights so burried under the harness was a voltage regulator. Disconnect this and I get battery warning light working and engine start stop as should. Check resistance through resistor and getting about 90ohms. Will replace and see what happens.