ULSD - More Clogged Fuel Filters
 

Definitely make sure you have spare fuel filters with you these days, the ULSD seems to be stirring up a fair amount of junk in the system. I drove back from NY to CO this weekend and was doing fine until about 200 miles from home, cruising 80-85 mph most of the way with no problems. After my last fill-up (in NE) I started to notice a little loss of power on the hills, but I decided to drive home instead of messing with it on the side of the road. By the time I got home, the car would barely exceed 75 on even a small hill (just about the same power as a 240D at this elevation). As I recall, I changed both fuel filters less than 20K miles ago. I need to change the filters this morning (and get a new spare). Hopefully, most of this stuff will get out of the system soon.

If you haven't changed the fuel filters yet, how do you know it's dirt and also that the ULSD is causing the problem? You might have gotten some questionable fuel someplace. Let us know what you find when you change the filters.

I just changed the filters and went for a little drive, problem solved. The clogged filter symptoms are pretty obvious once you know what it feels like.

I don't think it's the ULSD itself, but I do think it tends to loosen up all the crud that's been in the system for years. I had trouble blowing through the pre-filter, just black sludge. I didn't bother to cut open the big filter, I just replaced it anyway. I may have gotten some dirty fuel, but the last station I went to is a pretty busy truck stop. I think I just flushed some stuff loose, I drove about 4000 miles in the last week, so I've just run about 12 tanks of ULSD through it. Hopefully, I've gotten most of the big chunks out.

what is ULSD????

Ultra Low Sulfur Diesel.

That black sludge sounds like fungus to me. Tis the season. I have two 123s with this problem. I nail em with a strong jab (Startron), wait, then a right hook (biocide), wait, then startron a week later.

My car must have never had dirty fuel in it, as I ran biodiesel for a whole month a little over a year ago, and it never had any "junk come loose" or anything, I also ran a mix of fry oil and Diesel and RUG right in the reguar tank, ran great, still using that filter currently, 8k later. :D So far I have about 15k on my present fuel filter, and no issues yet.

I'm not sure if it's fungus or not. I just installed a clear pre-filter so I can keep an eye on it. If I see any more I'll dump in some Startron/biocide. The green fuel looks really strange in the clear filter.

The ULSD stuff almost has a light blue tint to it, 500ppm "lowsulfur" stuff is more green.......I think what I filled up with yesterday was ULSD, it looked blueish, and my exhaust smells quite different...

I can't really see the color difference between LSD and ULSD, but I'm pretty color blind. At this point, I suspect most of it is ULSD anyway. It does smell strange though.

Craig -

Glad you got it under control. I should have mentioned in my earlier post that, regardless of what fuel you use, carrying spare filters is always a good idea. I always carry two of the plastic pre-filters and one main filter. (Yeah, you older forum members know that, but I thought I'd include it for some of the newbies.)

Cheers,
Wes

i've never noticed the smell or color of ULSD, the color of LSD to me doesnt look green, and i have no idea about the shell premium i filled up with the other day, i hope its ULSD, the clerk at the counter had no idea and she tried to stop me when i was filling my car with diesel, she was like your going to kill your engine, i pointed to the trunk and had to explain to her mercedes benz is the fore runner in diesel technology in cars...

Craig, I'd be willing to bet that only your pre-filter was clogged. I went through lots of them after I started using WVO a couple of years ago in my '80 300TD. I also learned to shake the gunk out and re-use them several times. I did change the secondary filter once early on, but I really don't think it was ever clogged. After several thousand miles on 90% WVO/10% RUG, the problem seems to have cleared up. I think it was scum in the tank and lines from 20+ years of #2 diesel fuel. Steve

Probably true, this time the pre-filter had visible junk in it. I normally change them both at the same time anyway, it's just easier to do them both at once.

This is the color of the Shell I'm getting locally, I guess it's green?

What arethe symptoms like?
 

I think I have a fuel supply problem on my 240D too - but I'm not sure.

My car pauses - stop start stop start when I put my foot down. At low revs, it is OK, but not with the foot down.

It has a new pre-filter, and I checked the flow - it is much slower than the flow on my 124. So I thought maybe it was the tank filter. But running it on a bottle with my 85%WVO/15%kerosene (eliminating the tank) it still pumps really slowly. I have bled the system. I replaced the spin on filter fairly recently, if I remember correctly.

So my question is, is the loss of power (kind of jittery and jumpy) due to fuel supply? Or could it be air in the pump or IP (and would that explain the lack of fuel flow?)

How's that for a thread hijack? :o