I have noticed this problem with my x-reg 106 1.5 diesel
the short answerto my problem was the cables going into the ECU (silver box on the battery clamps) were dodgy to say the least
it is possible to start the car in this condition but it involves bump starting it.
you will not get rev counter / fule gage and the stalled light lights up, and it will drink fuel, run like a dog, and sound like a tractor due to not having the ecu powered.
the short of it is, the connectors are rubbish, and the placement of the ecu is just plain stupid (where it is always being moved for the battery).
I intend to replace the connectors with maplin / RS connectors
Jeff, October 2007