Hey guys, i have a 2001 ml320 having problems starting it takes forever to start and it looses pressure at the fuel rail after i turn off the engine.. as i thought this was the problem,I replaced the fuel pump(stupid place to put it under seat) and i also replaced the fuel filter(cost an arm & leg and hard to get to) and problem is still there loose pressure at the rail after i turn off the engine.......any help would be great!!

 

its usually the fuel filter. it has a regulator in it that holds pressure in the rail.