300D just shuddered & stopped running

[Ducati]

I have what I am certain is a fuel delivery problem. As it is raining like Noah's Flood up here, I am hoping to get advice on troubleshooting from you guys before I go out into the cold clammy garage to look for the problem & try to fix it. I have about 1/4 tank of fuel in the car, & there is fuel visible in the filter.
Late last night the car just shuddered and sputtered to a stop. I let it cool down (I dont know if this was neccessary, as the temp gauge read normal operating temp.) and put my foot to the floor & it started up again. I drove it three blocks home, where it again shuddered and stalled, unable to restart.
I have been using a product called "Diesel Treat" (I believe it is by Kleen-flo) that is supposed to lubricate the IP, inprove cetane, and eliminate moisture - 250 ml. per 50 litres of fuel.
Help! Any ideas? Until I get the Benz running, I have to drive a Buick Skylark...

[engatwork]

I'm sitting here wondering if you may have gotten some bad fuel. The first thing I would do would be to replace the fuel filters and topping it off with some fresh fuel. BUT - this does not really explain why it runs after you let it cool down some. When was the last time the valves were adjusted?

[psfred]

Crack the fuel return line at the filter and verify that fuel is being delivered when you operate the hand pump -- I suspect you have either plugged fuel filters or plugged tank screen.

Adding moisture removing fuel additives to an MB is a poor idea -- if you did have water in the tank, it is full of crap from stuff growing in it, and when you remove the water the crap ends up on the tank screen. It will plug while you are running, then fall off when the engine stops.

If you don't get fuel delivery with the hand pump, try blowing down the suction line and verify that you get air bubbling in the tank -- if the screen is plugged or the line is plugged, the car won't run.

If blowing down the suction line fixes the problem, you need to have the tank cleaned and the screen replaced.

Peter

[william rogers]

had the same thing happen in my SD when gauge read 1/4 , filled tank and it ran fine.....faulty gauge?
William Rogers....

I was going to suggest the plugged filter too, just because you can see fuel in the filter does NOT mean it is flowing THROUGH the filter! Been there done that!

Peter: can you get to that "sock filter" in the tank without removing it? I havn't tried yet, but as long as this car sat before I rescued it I KNOW there is crap in there! I was also wondering about whether it was possible to remove the drain plug in the bottom of the fuel tank and take out the sending unit and get a respectable "flush" this way? Heck, I may even be able to get my arm in there far enough to wipe it out with a lint free cloth. ( Please note LINT FREE) Tom

[psfred]

Tom:

The sending unit/fuel outlet on the W123 and W126 is accessable by removing the first aid kit floor in the rear package shelf. Take out the first aid kit and there are some screws that hold the trim panel down. Underneath is the top of the tank.

Needless to say, one should be somewhat careful not to liberally decorate the rear seat with diesel fuel!

I would be very cautious about adding "water absorbing" fuel treatments to diesel fuel -- if you add enough of something polar to the fuel to get it to absorb water, you've added enough to impair the lubricating qualities. I've never seen one or heard from a reliable source that it happened, but the thought of wrecking the IP by running fuel with insufficient lubricating power through it is frightening!

If the drying agent doesn't actually dissolve the water in the fuel, it will absorb into the water, increasing the volume of the water portion, and if THAT gets through the filters and into the IP, it is replacement time.

Ditto for adding gas treatment to a tank with sugar in it -- the only two times I've seen actual damage from sugar in the gas were a small engine carb completely plugged with syrup and the roasted crap from the combustion chambers of a Taurus that had sugar in the tank -- when the car ran like crap from fuel starvation, Dad put in de-icer (it was winter) thinking it was ice in the fuel line.
Dissolved the sugar in the methanol, ran through the filters and injection system, and turned into caramel in the combustion chambers. Ugly, had to get a new engine! Bent rods, bent valves, scratched cylinder walls.

Normally, if there is no water in the tank, sugar won't dissolve in gasoline -- just sits there and plugs up the fuel inlet. Sand will do the same thing!

Peter

[P.E.Haiges]

MY '80 300SD was acting strangely when the fuel in the tank got below 1/4 full. I drained out the fuel (~ 20 gallons) by taking off the end of the rubber fuel line where it connects to the steel fuel line. That way it was easy to direct the flow into 5 gallon buckets. The fuel ran out fast until the tank started to get empty. When the flow was almost nil, I removed the in tank fuel filter which comes out from the bottom of the tank. This filter which is really a screen, was plugged about half of its height. So I cleaned and replaced the filter and put the fuel back in the tank. I haven't run the car low on fuel since, so I don't know if this fixed the problem, but the problem found matched the symptoms.

To make a long story short, what I suggest is that you check your in tank filter. It costs nothing and isn't a difficult job.

P E H

I don't have to remove all that stuff to get to my sending unit, nor do I need to worry about getting fuel in the interior. My 300D is a W115, therefore to get to it all I need to do is open the trunk and pop out the cover plug! Tom