let me start with this:mad: and this:banghead:...................ok now moving oni had problems with my truck somehow letting a tiny bit of air in....so i posted a thread before and all fingers pointed to the teflon tape i used on the fittings of the draw straw.so....i purchased myself a can of permatex prepping solution, and a tube of the high temp thread sealant. I sealed all the treads at the draw straw, and the one fitting at the pre filter. I allowed it 72 hours to dry and fired it, and it ran fine. I shut it down after 3 mins of running and started it back up 2 minutes later, same thing fired then chugged like it was missing for about 5 seconds. Today i came home and changed the fuel filter and to my suprise i found this..........my fuel filter looked more like an oil filter, it had black sludge all over it. the truck has 168xxx on it and i dont know if the fuel filter was every changed, it sure didnt look like it. But the fun didnt stop there......yep thats METAL SHAVINGS in the bottom of my filter housing. i have no idea how in the world they got there. bottom line is the fuel filters fresh and it started and ran fine. im going to go back out and start it again in an hour to see what it does. the one question i had is this, in doing all the things ive done thus far wih the fuel system, i havent removed the pre filter. if i start it and it runs like crap again does this mean that my pre filter could possibly be clogged???? i read alot about guys taking them off and never really finding anything in them.

Apparently you do have a air leak some where. If you have to prime the system that many times. Where is the question?

Sorry I must correct myself.i dont have to prime it every time i start it. i primed it that many times because ive been doing alot of fuel system work and prime it every time i pop a hose off or take the fuel filter off etc.the question is, because ive bled it so much, could the copper washer under the bleeder bolt be the issue?

Well technically the bolt will be pressurized after the engine is running so as long as the bolt is not leaking while the engine is running I'm going to have to say no. But now all the fuel lines rearward of the lift pump would be suction lines and can leak without warning. Because the air will leak into the line draining it back to the tank.

all my fuel lines are new, from the tank to the prefilter, and from snap on part of the return line to the tank. all lines are now rubber as well.

Well my NASA thing requires some fancy fittings. The 2nd fuel port is M18 x 1.5 and going from that to a hose barb or something isn't something that any local stores sell. I would look all over it on the return lines and other stuff for any sign of fuel leaking since that would also be a spot for air to leak in. Air being thinner than fuel it might be hard to pinpoint, hence my NASA thing. I worked on a truck that had biodiesel hooked up to it which made him cut all the steel fuel lines and run rubber hose. He had an air leak and I replaced the rubber hose with clear rubber hose and mann was it easy to find. I would almost cut all my steel lines if it wasn't for the fact that steel lines are obviously very stout and will only leak at the fittings.

I need to jump in here, I just looked at this thread for the first time. You need to get that fuel out of the tank and clean everything out good.The black stuff in the fuel filter and screen is Fuel Algae which you should have caught on to in one picture you actually posted.You got a bad load of fuel somewhere and or got a load of water with some fuel which promotes the algae growth.You need to run a couple bottles of bio kleen or similar product through it to kill it.You will just keep the process going unless you get the system cleaned out. There is one other thing that can cause that black residue in the filter but that is found on HEUI "Hydraulic electronic unit injector" engines where the fuel is under extreme pressure and heat and returns to the tank for cooling I can't remember the term for this right now but it is a break down in the fuel from heat similar to having soot in your oil.

Where does the algae come from and what causes it? I have never dealt with it and don't see why it looks like oil. Thanks for jumping in on this!

DANG so i gotta take my module out and clean my whole tank? it has about a 1/4 in it now, would it work to put it back together and run the fuel thats in the tank, then fill it back up and and run bio kleen in the next tank?? i thought algae came from sitting over time thats why it didnt raise a red flag to me.

Algae usually originates in bulk tanks that have moisture in them from condensation not necessarily from your own tank. It looks like oil because its waste is essentially a black slime imagine it as a type of slimey mold or pond algae it is microscopic but it just coats the filter like what you see in the pictures.You could run the tank empty and then fill up at a known good station and add an anti algae formula of some sort there are many brands get what you can get locally, most truck shops or truck stops should carry it.Any type of diesel is prone to algae but it is becoming more prevelant with the new Bio diesel blends.Us long term diesel techs like to refer to this as diesel Barnacles :lmao:You can do a search on diesel fuel algae and find tons of info on it.

I've had to deal with this over the years. It looks like black snot and can take time to get rid of it all. Once you start killing this stuff with the additives it will break loose from the sides of the tank or lines and follow the fuel flow. You will want to keep a few extra filters on hand because they will plug up quickly.

From Wikipedia:

[h=4]Algae, microbes, and water contamination[/h] There has been much discussion and misunderstanding of algae in diesel fuel.^{[25][dead link]} Algae need light to live and grow. As there is no sunlight in a closed fuel tank, no algae can survive, but some microbes can survive and feed on the diesel fuel.

These microbes form a colony that lives at the interface of fuel and water. They grow quite fast in warmer temperatures. They can even grow in cold weather when fuel tank heaters are installed. Parts of the colony can break off and clog the fuel lines and fuel filters.

How can you tell between algae and just contaminants on the fuel filter? My fuel filter looks the same as his but I don't get oil on my hands when I touch it and it's not slimy. Mine is more like just a fuel filter that someone colored black, the media feels the same as new.

Slimy is the key. You'll know it for sure if you get some on your hands.

How can you tell between algae and just contaminants on the fuel filter? My fuel filter looks the same as his but I don't get oil on my hands when I touch it and it's not slimy. Mine is more like just a fuel filter that someone colored black, the media feels the same as new.

Thanks for adding some facts to the discussion bh. ISX the microbs or algae scrape off and feels like oily slime and plugs the filters up fast. as the info db posted above. It takes time to get it worked out of a system. The blackness you describe in you filter is totally normal as the fuel has additives and dirt and other things in it that will turn a filter dark over time. but the barnicles are thick slime and like to congregate.

Here is a bunch of info. Looks like they are trying to sell their product so maybe take it with a grain of salt. I've had good luck with Bio-con from Napa. http://criticalfueltech.com/faq.html

WHEW thats a sigh of releif, taking the module back out and all wasnt sounding fun. so i guess the truck will be idleing in my driveway for a while once its back together . i will be making a stop at my local NAPA today on the way home to see what i can find.i cant thank the people that have chimed in enough. you guys really are top notch cummins owners

WHEW thats a sigh of releif, taking the module back out and all wasnt sounding fun. so i guess the truck will be idleing in my driveway for a while once its back together . i will be making a stop at my local NAPA today on the way home to see what i can find. i cant thank the people that have chimed in enough. you guys really are top notch cummins owners

You can change the filter 12 times or you can drop the tank and clean it out. I myself would clean the tank. The constant worrying about when the filter plugs and where you will be left sitting isn't worth the hassle in my book.

i have the bed off so all would have to do is pull the module and suck the fuel out. if i go this route what would your suggestion be for solution to clean the tank with?? also can i burn the fuel i pump out of the tank? or should i fill with good fuel and disregard the contaminated fuel. at $4.23 a gallon its like gold anymore.

i have the bed off so all would have to do is pull the module and suck the fuel out. if i go this route what would your suggestion be for solution to clean the tank with?? also can i burn the fuel i pump out of the tank? or should i fill with good fuel and disregard the contaminated fuel. at $4.23 a gallon its like gold anymore.

I would settle out the fuel and pump out the top 90% of it out of a 5 gallon buckets. But remember if it is algae problems the fuel is technically contaminated. But I agree with Wild and Free its best to clean the tank really good and start over. While your at it I would blow solvent through the fuel lines too... Make sure there is no other gunk floating around. Then monitor the filter housing... Sample some of the fuel in a clear bottle or such and see if anything shows up.

will simple green or some kind of cleaner work to wipe the inside of the tank down with?? And what exactly can i do with the diesel once its out. thinking that its contaminated the only thing i can think to do is dispose of it and start fresh. would it be possibly to mix it with fresh fuel later or should i just follow my gut and get rid of it?? Also what kind of solvent should i use to flush my lines??and heres the plan I've devised for this weekend-1) re install my lift pump and clean pre filter assembly.2) pull the module and pump the fuel out into a 5 gallon container.3) use whatever the recommended cleaner is and wipe down the inside of the tank.4) dump 5 or 10 gallons of fuel back in the tank and whatever additive i end up with and re install the module5) hook the lines back up and fire it

will simple green or some kind of cleaner work to wipe the inside of the tank down with?? And what exactly can i do with the diesel once its out. thinking that its contaminated the only thing i can think to do is dispose of it and start fresh. would it be possibly to mix it with fresh fuel later or should i just follow my gut and get rid of it?? Also what kind of solvent should i use to flush my lines?? and heres the plan I've devised for this weekend- 1) re install my lift pump and clean pre filter assembly. 2) pull the module and pump the fuel out into a 5 gallon container. 3) use whatever the recommended cleaner is and wipe down the inside of the tank. 4) dump 5 or 10 gallons of fuel back in the tank and whatever additive i end up with and re install the module 5) hook the lines back up and fire it

After you get the fuel pumped out and wipe all the residue and scum out I would just wipe it down with hot water with bleach to kill any other critters in the tank and then put clean fuel in with anti microbal of your finding. I would just blow the fuel lines out with air if you have some if not that isn't enough to cause much more than one more filter change after running a full tank of anti algae solution through it and you should be fine. The old fuel could just be taken to any used oil drop off do not remix it as you will just reintroduce the critters back into the system again. Or you could use it to start your bon fire. I would start checking the last few places you filled fuel and tell them about your problem and that one of them most likely is causing a lot of other people the same issue as you are having. They all have the means to pull fuel samples and have it tested for microbes.