petsmud

i got a w203 c270 cdi i changed new fuel line with new o rings and the fuel filter because i was getting a very hard starting leading to battery drainage hoping i will solve the problem but it can start first few days there after it starts giving the same problem if i check on fuel line from filter to the pump i could see a lot of bubbles after raving too much they clear a bit but when i park it the fuel line will be empty without diesel no leak meaning its returning to the tank pliz can anyone help why its returnig diesel

Plutoe

Air in the low pressure diesel fuel lines means air is being sucked into the line---go back and review your work------you did use new parts---correct---- not junk yard crap!!