I hadthe same trouble last month. I have been changing the fuel filters in my 1983 300SD since 1988 and had no problem. The last time I could not get the car started. With the help of this forum I was able to determine hat I needed a new hand punp (mine was leaking). Had alot of air in the line and after following the guidence of the members of the frum (and 4 battery charges) it worked. Takes alot of cranking a real pain.