Questions about replacing fuel lines
 

I am completely new to diesel engines and i was wondering if i need to prime the fuel lines after i replace them, or just try to turn it on until the fuel reaches the engine and starts up, and if so, how do i do it?

If you replace the supply line and the return line at the tank you will definetly want to prime the lines before trying to start. If you are just replaceing the lines under the hood you don't have too, but it will make it much easier to start up the first time after the change.
Pretty sure the sedans are like the wagons. On my wagon the supply and return lines are on the bottom of the tank which requires a nearly empty tank to remove the lines, unless you want 20 gallons of diesel all over the place, or you better have a big storage container.
Make sure you put a cigar hose back in place of the old one. I put a straight hose on and teh car starting making a pulsing noise. Put the cigar hose back on and it went away.

Also Diesel Giant has a DIY Fuel Hose Install--http://dieselgiant.com/mercedesfuelhoseinstall.htm

Depends on which model car you have.

Depends on the car.

Yes, it does depend on the car. They come with these little books in the glovebox that tell you just how to do it.

o, heh thanks, btw i have a 1979 300sd but yeah, i'll look in my owner's manual

Your car has a primer pump, near the inline fuel filter. After you reassemble everything, you need to pump it quite a few times (maybe 30 seconds). Try to start the car, if it doesn't start after about 15 seconds of cranking, pump some more. BTW, use the same procedure when you replace the fuel filters.

When pumping the primer pump, the sound will noticabley change when fuel actually starts making it to injectors. It does take a while though.

If it doesn't seem to be doing it, even after LOTS of pumping, or if you see leaking around the primer pump, it may need to be replaced. There is an 'old version' that has a round white knob on the pump handle, and a 'new version' that has a black round cylinder as the main pump handle. If its the old version, and doesn't seem to be 'doing it' for you, then you may need to replace it. Its easy and cheap.

peace,
sam