Got in the car yesterday morn. waited for the glowplug light to go out,hit the start,she sounded like she would go and didn't. Now it just cranks, checked volts to glow plugs (new last year) and it's there. (10.3VDC) Tried today and same thing, only if I hold the accelerator pedal to the floor, she tries to start but can't pull it off. Sounds like it's out of gas, could the fuel filter be clogged? It's been on for about six months (15,000 mi.) What can I do myself, besides call a tow truck? My dealer really sucks, had this car in last week for a rough idle, they said they could not duplicate! Week before for a noise in the front end ( two trips) could not duplicate, I fixed it, it was sway bar bushings. So you see why I can't trust them.

Similar experience
 

Prior to my current 300D I had a VW Jetta diesel, that acted like what you described. Turned out the fuel pump inside the injector pump was worn out (this is what sucks fuel from the tank before it goes to the high pressure injector lines). I removed the injector pump (this was not an easy job) and had it rebuilt by a specialized diesel injector pump shop. Cost $500 which was 1/3 cost of buying a remanufactured pump. I put the injector pump back in, bled the injector lines, and the car started immediately! Wear on these pumps can be caused by Govt.-mandated low sulfur fuel that does not have good lubricity. Question is, how do you know if the injector pump is bad? If you are cranking the engine and the pump is working but the car is not starting, normally you will have fumes/vapors of unburnt diesel fuel coming out of the tailpipe. If nothing is coming out of the exhaust during cranking, look for a fuel problem.
Another thing that brought down yet another diesel I had (1980 Olds 88 with 350 cu-in diesel) was fungus growing in the tank that clogged up the fuel sock. The dealer's expensive solution was to drop the tank, drain and flush it. A cheaper solution is to buy a tube of diesel anti-fungus stuff available at many truck stops (on two other occasions I did this and it worked). It kills the fungus; then you should replace the fuel filter because the dead fungus can clog it up. Fungus can come from many sources, including condensed water in the bottom of the tank where fungus and bacteria grow, or could be pumped in with fuel if you buy diesel from a low-volume place (always buy diesel fuel from a high volume truck stop if possible!)
Hope this helps... Bill

Volts sound low. I like to see 10.9 and above for cranking.

Be sure you have fuel. I would look at the pre filter with a light to see if it is full of fuel.

Get someone to crank the engine while you crack open an injector line at the injector. If you have fuel there then your glow plugs have quit (most likely problem).

Do you think the fungus thing would apply to this car if I use more than a tank of fuel a week, it doesn't sit around much. When I purchased this car a few years ago, I purchased a new pre filter, however I have never been able to locate it on the car, any hints where it may be hiding?
Is it likely that all six glow plugs would go bad at the exact same time? When I had a glowplug problem before, two of them were not getting hot, but the thing started right up every time. I really hope it's not the fuel pump, can't imagine what that would cost?
Thanks for all your help!

The pre filter should be located near the fuel pump on the right side of the engine (standing in front of the car) between the incoming fuel line and fuel pump.

Normally glowplugs do not go bad at the same time (if so, there is a problem with the glow relay or the fuse in the glow relay).

It sounds like your car is out of fuel; check the fuel at the pre-filter or injector line while somebody is starting the car.

greetingz,

The fungus thing
 

Sometimes this fungus grows in the gas station's tank. The problem is worse if you buy fuel from a smaller place that doesn't turn over fuel so often (i.e., not a high-volume truck stop), because the fuel sits around a long time.