Hi and thanks for taking the time. This is my first Mercedes but my ninth diesel and I can generally find my way around but this one has me a little bamboozled. The car has new fuel filters and runs really good; however about two weeks ago I thought she could have been loosing power ( just every so slightly ). I ended up passing it off as strong headwind gusts as when I changed directions the problem went away. I travel 45 highway miles each way to and from work. Anyway on the way home today about a mile from my house she started loosing power ( like she was running out of fuel ) the fuel gauge was bouncing from empty to ¼ tank and we glided to the side of the road. When I got out and looked there was fuel in the filter and fuel line and I know I should have about ¼ tank of fuel. I let her sit about 3 minutes, started her up, fluttered the throttle a few times and drove home like nothing had ever happened. Note the fuel gauge was steady the rest of the way. If not for the erratic fuel gauge I would be thinking I have a fuel line collapsing. Any thoughts or suggested starting points.

Thanks
BarryO

 

It sound like you have a fuel restriction. Look under the car at the tank, swap the return line with the supply line, this will tell you if the strainer is plugged up, if so run the tank empty, and remove and clean the strainer. By letting the car sit for a few minutes, whatever was against the strainer fell off enough for it to allow fuel through.

 

Great idea of swapping the lines I will most certainly do that first. I was thinking of removing the tank and do a thorough cleaning of it as well. I have had the car about two months now and generally don’t let her drop below ½ tank. After I had posted I realized I neglected to mention that she has done the erratic fuel gauge dance before but only at about ¼ tank. I realize from looking at the fuel diagram that the sending unit has nothing to do with a fuel restriction but was wondering if fuel sitting in the tank for a very long time could be the culprit of both the erratic gauge and the fuel restriction.
As a side note the gauge is extremely accurate.

BarryO

 

Is the tank ventilating properly? If it isn't then you take the chance of collapsing the tank especially durring a long run. Try taking the cap off right after driving it for a while, see if there is a vacuum, there shouldn't be or if there is it shouldn't be very strong

 

Funny you should ask about venting, ( I was reviewing the vent tank info this morning.) But to answer your question, I don’t know? I have not noticed any pressure release when removing the cap. But I fill up at the same station, same pump, 9 out of 10 times and I have to go inside first so by the time I get to removing the cap it could have already equalized. I will make it a point to look for that in the future.
I am going to go put her on the ramps,take look and see what I feel up to doing today.
I will probably siphon the 4-5 gals of fuel out and check the screen.
I love the smell of diesel in the morning, but I don’t care for the taste.

 

OK, A little help here.
I just got through draining the fuel tank and was attempting to remove the screen filter from the tank, but it will not budge. I slipped the line through a boxend wrench to get the most secure position I could but the whole thing is flexing and I am afraid I could break the plastic tank. I was thinking I could just plug the fuel line and pull the whole thing through when I remove the tank.. Once out I could use two wrenches to offset each other, plus I would be in a much better position.
Suggestions.

 

Never mind. Went back and just held a steady pressure on it and it broke free. I got the screen out and it is covered in black goop. I will post a picture in a few minutes. I just wanted to post that I got it out before someone did a dissertation.

 

Hope I did this right.

 

I don't know why the picture did not post, maybe it was to large. But the goop looked like black elmers glue.

 

Has someone been using motor oil as a fuel? Kind of makes a mess. Especially if it isn't filtered properly, and then sometimes it still makes a mess. Looks like elmer's glue, or a little thicker. It also could be algae.