a friend of mine has a W reg Mk4 Astra Van 1.7 DTi with the vauxhall engine in it. this morning and ever since it keeps stalling. he had someone to look at it and basically if you lock and inlock the van it will start again and run for a few mins then stall. the bloke says its the immobiliser but has something to do with the diesel pump?? he said that it requires a new pump but im unsure as isnt there a electronic diesel control unit on these engines?