Hi

This car came in on the end of a piece of rope after cutting out on dual carriageway,i dont think the fault code is anything to do with non running?
fuel supply to tandem pump/high pressure pump seems poor although it is a steady stream have tried inline pressure gauge but does not register so removed in tank pump to find layer of black "scum" on everything so replaced in tank pump and filter,but no difference engine fires but will not run as before.I think the black scum is possibly injector seals leaking but i do not think this should stop it starting?any ideas or tests i could do would be much appreciated.

thanks.