what is this black stuff?
 

today in a hopes of solving a miss at idle, and rough idle after changing delivery valve seals and washers, see thread:

http://www.peachparts.com/shopforum/diesel-discussion/365524-new-delivery-valve-seals-now.html

i replaced both my fuel filters. upon taking the old small one off i noticed black sand spec stuff on the screen.

then i noticed after driving about 50 miles today the new one already has some on it!!!!

wth is this stuff?

link to miss at idle and noise from engine. engine was at temp.

https://www.youtube.com/watch?v=lrCZYL4UdTo

Errr. Not good. Try taking a sample from the bottom of the tank - if it's not there, the insides of your fuel hose/line is coming apart (replace/flush). If it's in the tank, I dunno, maybe dirt, maybe biological remains (clean tank). Aren't you glad your system has a filter? In any event, start carrying a couple spare filters till you get it sorted.

In two words...dirty fuel. If it was gooey and slimey, it would probably be fungus. However, this is probably from fuel that has sat for a long time and some of the tars have settled. I had this from a fuel stop on a trip. Fought it for a long time until I ran a bunch of biodiesel through the fuel system and eventually it cleared. Use quality fuel filters and several spare pre-filters.

The best thing that eliminated the majority of it was draining the tank. It is pretty easy to do from the hoses on the bottom of the tank. (Do it when the tank is low on fuel and have several containers on hand. I used a double-barb fitting, hose and locking pliers to pinch off the hose between containers.)

I'd recommend using some bioshock just the same. If it is a fugal growth you don't want to let it get worse...

Feels/looks gritty. Like dirt. I remember getting fuel one time where I normally do and the pump was REALLY slow. Like 4 gallons in 5 minutes slow. I was probly suckimg the crap off the bottom of the under ground tank.

I would like to do some biocide for good measure, the car sat for 7 years before I bought it, but that was 1 year and 8k miles ago.

Where can I find biocide?

Those of us with old diesel boats have seen a lot of that black sandy looking stuff. It is typically called asphalteens, and comes out of aged diesel fuel. The low sulfur diesel used an extract of asphalt, which would come out of solution over time. I would be surprised if asphalt is used in ULSD but it could be on the bottom of your tank. It can be dissolved by Startron tank cleaner, and likely by regular Startron used regularly. I have spooned it out of my sediment bowl on my boat. It is not microbial, fungal, or algae.

A 606 with leaky fuel lines for too long had this all in the 3 hole. I was like wtf? Did so done put oil dry to sop it up? This explains it. Thanks

In my experience black specs have always been bacterial growth. It is commonly found in fuel. Water causes it to grow. No water, no bacteria. Using biocide has always worked for me. Its available at serious truck repair supply places, and at farm and marine supply places.

Automotive diesel is a lot different than the bunker fuel burned in large marine diesels. Our little diesels would not run on that stuff at all, I don't think.

This is an excellent product, and can be found in most marine supply or automotive stores.

Star Tron 8 oz. Diesel Fuel Treatment

Bacterial growth is gooey, not grainy. Bacterial growth WILL cause the grainy sediment, but it is asphalt. The bacteria break down the fuel leaving asphalt. Treating for bacteria often solves the issue because the chemicals break down the asphalt also.

i treat every tankful with stanadyne. is the tank cleaner from startron any different?

Do you have a source for this process of bacteria eating fuel and leaving asphalt?

Well... Everyplace that explains the issue...

Frequently Asked Questions About Diesel Fuel Problems

http://engines1.novosolutions.net/default.asp?id=275

http://www.diesel-fuels.com

It is rare that I would argue with you John, however....

I did not find anyplace in those that explained the phenomena of "asphalt" being a by product of treating with biocide. I am pretty sure there is a scientific definition of asphalt that does not include being produced in a fuel tank as a by product of using biocide.

They all appear to be advertising web sites.

One of the websites stated that the way fuel is refined is much different now than it once was. I don't have any knowledge of that. Has it changed in the last five years?

I know the sulfur has been mostly removed, does that impact the bacteria growth?

Every time I have found my filters clogged with black specs I have changed filters and treated with biocide and had no further problems.

I have driven a lot of miles in diesels, having owned ....25 or so and have never cleaned or replaced a tank strainer (that I can remember) or removed a tank for cleaning.

I do know that every site you linked offered a product which would solve all problems with bacteria....nothing wrong with that but I think we all know that advertising often parades as science but seldom is.

Have a happy valentine day!;)

There should be no asphalt or tar in ULSD fuel, it should have been refined out of the crude during the distillation process. Where do people come up with stuff like this? Please provide some scientific proof/ tests that it is asphalt/ tar and not Algae, which is black. like asphalt/ tar.