Engine wont turn off with ignition

[steviedee]

I have a 1.9 diesel fitted to my T25 that came from a Polo - non turbo. Its starts ok but when i turn the ignition off and remove the key - it still runs! I've had to wire in a switch to cut the circuit for now but any suggestions ? Could it be the actual ignition switch? (I didnt have this problem prior to swapping the old 1.6 diesel for the 1.9)

[California Dreamin]

Faulty fuel cutoff solenoid (not shutting off the fuel going through the diesel pump)
Or as you imply.....ignition switches are prone so you need to check the feed going to the solenoid to be sure.

Martin

[colinthefox]

Faulty fuel cut-off solenoids usually go faulty the other way round, like they won't open when 12V is applied, but that is certainly worth checking. If that fails, and you've checked the ignition swith, then you could try this:-

If there is still 12V on the solenoid when the ignition is turned off and the engine still runs, it is possible there is a backfeed from the D+ terminal on the alternator, through a faulty component on the dash circuit board and back to the solenoid. To test for this, disconnect the D+ connector from the alternator with the ignition off and the engine still running. If that stops the engine, there's your problem. Long shot, but awkward to find if you're not aware.

[kit]

Use the old solenoid from your 1.6 pump it ha a spring in to shut off the valve when the power is off whereas I believe the solenoids in car engines do not as they are vertical and gravity does it, had the same problem when I fitted a 1y.