I have made the mistake of letting my mondeo run out of diesel whilst valeting it the other day. (And yes I do know better than to run a diesel car low on fuel, I was unaware it had been used and left back empty by another member of the household)
Anyway, I have put about 20 litres back in, and have now run the battery flat twice cranking it over........ I have been told it is a self purging system.
I have replaced the fuel filter and filled it with clean diesel today before trying to start it again.