Black stuff in fuel filters

It could be soot, ive seen this happen when injector hold down bolts stretch and lift up under pressure, blows soot back into the fuel system. Every time i pull the top rack off ill replace the bolts as they do stretch.

 

Well if you think about it each pistons stroke per cylinder is going push soot out, so yes its a possibility and ive seen it happen.

 

Ok.... soot is not going to go back up the fuel rail and end up in a fuel filter.

The primary cause of this black fluid is bacteria that loves to live in diesel fuel. This is algea that grows and is the source of the black you are finding in a filter.

The ONLY cure for this is to get some biocide that will kill these critters. Racor makes a great biocide that you can get online. Just do a google on Racor Biocide.

I have experienced this problem a few times over the last 25 years and it is always the same. If you don't get a handle on this junk, it will totally destroy a fuel system.... lines and all. You have to dose the fuel with a "shock" level of biocide for the first couple of tank fulls, then you will have to run a maintenance level of the biocide for quite a few fills just to make sure they don't return. These little guys reproduce real fast. You will go through a few filters doing this. Their little, dead carcasses will get snagged by the filter and cause it to plug up pretty quick, depending on how bad they have grown throughout the fuel system.

Good luck!

 

You have never seen stretched injectors hold down bolts then.

 

I agree with 550, failed lower injector seals or loose injector can cause black fuel. Seen it many times. Older 3116 engines with brass cups with air in the return always had black fuel.

Also that primary fuel filter number, thats the smaller one, do you have the room for a 256-8753. Its abit longer but has higher fuel flow. Have you checked you fuel pressure? Possible boost leak? Do you just pick up some dirty fuel? Do you check the bottom of your tanks with a bright flash light, you can see whats left on the bottom.

 

It all sounds good, but what if it is algea in the fuel. Better to dump a little biocide into the tanks when you fuel. Stuff doesn't cost that much to use. You might have seen an injector(s) do this, but it is not that common. A load of microbes from a bad load of fuel is far more common. Sometimes the simplest solution is the best. At least it is an easy, cheap start.

That's ok.... it isn't my tractor, so I'll not lose any sleep over it.

 

your engine is putrefying,roting,decomposing ,lots of dead bacteria corpses,carcasses in it
maybe your whole fuel line is contaminated,infected,pathologicaly sick in the worse kind of way...........................................................................................

 

I bet its "diesel bugs". Remember when dealing with trucks-the impossible will happen.Didn`t know about the biocide,thanks for the info.