ml 320 cdi 2006 fuel pump

[joedunmore]

hi

I am after a little bit of help I have a 2006 ml 320cdi and it has just started making a very loud whining noise it sounds as tho it is coming roughly around where the fuel tank is just under the drivers side rear door is this what it could be?? but I also understand there is 2 different fuel pumps is this also true??

thanks in advance