Hi all, hoping someone can point me in the right direction with this.
My 90 (Disco 200TDI - if that has any bearing on the fault) starts and runs fine.
Problem is when I come to stop and turn/remove the ignition key, the engine continues to run. I can only stop it but stalling it in a high gear.
Anyone have any idea of where to start looking please?

Stop solenoid on the f.i.p.

The only way to 'stop' a diesel is to take away the fuel or stall the engine (not recommended as a long term solution).

When you turn the ignition key 12V is sent to a normally closed solenoid which is just below where the fuel comes in at the back of the fuel injector pump (f.i.p. as per @GRATCH above), the solenoid opens and fuel can get into the pump.
When you turn the engine over it starts and keeps running.

Normall, when you take the 12V away the solenoid closes and the fuel flow stops.
The solenoids can fail and stay open.

Here;'s the part you need ,,,

and here's how to change it ...

NA1961 said:

Hi all, hoping someone can point me in the right direction with this.
My 90 (Disco 200TDI - if that has any bearing on the fault) starts and runs fine.
Problem is when I come to stop and turn/remove the ignition key, the engine continues to run. I can only stop it but stalling it in a high gear.
Anyone have any idea of where to start looking please?

Click to expand...

I can only think of 3 things.

1. On the back of the injector pump (below the rubber cover on the throttle cable where it attaches) is the stop solenoid. It has an electrical connector. Use a tester to see if it has voltage all the time. If so you have a short somewhere. It should only see voltage with the ignition on and when running. When you turn the ignition off it kills the voltage which causes the solenoid to close and stop the engine. I guess a faulty ignition switch could also cause this, but very easy to check.

2. The solenoid is jammed open somehow. Unplug the connector and see if it will start, it shouldn't. Or have the engine running and then unplug the connector, it should stop the engine.

3. It is running on its own oil. Probably less likely and would tend to have runaway revs. And would mean engine rebuild time.

On mine - although its a 300 tdi - if the lights are on the motor wont switch off = so thanks to Lucas, the prince of darkness - your issue could be elsewhere

300bhp/ton said:

. It is running on its own oil. Probably less likely and would tend to have runaway revs. And would mean engine rebuild time.

Click to expand...

You can get "partial" diesel runaways, where it runs on a bit on the oil, but doesn't rev up.

But I think he would notice from the smell of burning engine oil, and lots of smoke out of the exhaust.

So thinking the stop solenoid more likely.

All sorted - thanks everyone for the advice. As suggested, i t was the fuel pump solenoid that needed replacing. The video from Mike at Britannica was really helpful as it is really difficult to get to.

I made the suggested spanner with the help of a grinder and a blowtorch to bend it a bit. (pictures below)