how can i fix my 2003 transit 2.4 td fuel problem?

i have a 2003 transit van. 2.4 turbo diesel.at just under half a tank it stalls ,i bleed fuel system & goes alright for a couple of kilometres,then stops again.iadd diesel rebleed then stops again. i removed fuel tank to check for a faulty sender unit but there was about 35 liters of diesel.just wondering if any one else has experienced a simalar problem and what they did to rectify the problem? any help would be appreciated!