csnow brings up a good point - check connections for snugness, etc.

Something else to think about is the filter that was used.

Part 002 477 13 01 was designed for single pump systems.

Part 002 477 44 01 was designed for dual pump systems.

See the following URL:

http://catalog.eautopartscatalog.com/smittys/ap/wizard.jsp?partner=smittys&clientid=aplusparts.com&baseurl=http://www.aplusparts.com/&cookieid=0UV171X5G&year=1991&make=MB&model=300-E-002&category=E&part=Fuel+Filter