I have narrowed my problems with starting down to a likely two problem issue.
As a reminder, the car is a 1995 E34 525 TDS touring...

Can anyone confirm whether the pump on top of the fuel tank has / should have a non-return valve in it, so each time the ignition is switched on it doesn't push a pipeline full of air towards/into the injector pump, which then tries to inject it into the engine, which doesn't start except after two or three minutes of cranking, which is very bad for battery, starter motor and my nerves ?

I think the air is getting into the supply pipeline from an injector which is sticking open (sometimes) after switching off, and I think that is the other part of the problem.

I await with interest........


Nick