2012 D6K Fuel System Problem

PWR · May 27, 2017

We are having problems with our D6K fuel system. Throwing code but no problems show up on computer. Losing power. Appears to be problem with the high efficiency fuel filters. When those are replaced all is well for a while then problem reappears. As near as we can tell it is a problem with the fuel. There is a black film inside the tank. One mechanic says it is a fungus in the tank. Has anyone experienced this problem? Mechanic says take tank off and steam it out. Will this work or will problem just return? Need proven solution.

Birken Vogt · May 27, 2017

Most truck tanks I have looked inside appear to be as clean as the day they rolled off the factory floor. Since they are so easy to shine a light into.

If you clean the inside of the tank, you will have removed 99% of the possible contamination. If it is not somehow reintroduced, by way of water or more bad fuel, one more filter change should take care of it, in my opinion.

The question is how did it get there in the first place. Is the top of the tank leaking somehow?

DMiller · May 28, 2017

Not fungus, algae. Grows naturally in old diesel fuel. Most good fuel suppliers put algaecide in their fuel but it only lasts a few months to a year(s) depending on how stored. Once it starts you have to get 99.9% of it out of the tank or will repeat.

farmerlund · May 28, 2017

I bought a 973C a few years back that had the algae in the tank. Looked like there was hair in the fuel strainer. Slimy weird stuff. I treated the tank with the algaecide, and cleaned the stainless strainer along with a few filter changes. That fixed mine.

PWR · May 28, 2017

Looks like best solution is clean out tank and put in some algaecide. Think it came from some old fuel from fuel tank we have not used in a while. Only seems to be affecting one machine. Going to treat all of them.
Going to steam clean out tank. Thanks for the help.

Rob Marshall · Feb 28, 2019

PWR said:
We are having problems with our D6K fuel system. Throwing code but no problems show up on computer. Losing power. Appears to be problem with the high efficiency fuel filters. When those are replaced all is well for a while then problem reappears. As near as we can tell it is a problem with the fuel. There is a black film inside the tank. One mechanic says it is a fungus in the tank. Has anyone experienced this problem? Mechanic says take tank off and steam it out. Will this work or will problem just return? Need proven solution.

Have you

Rob Marshall · Feb 28, 2019

[QUOTE="Rob Marshall, post: 797138, member: 7674 I have the same issue.have you cured your problem?

Nige · Mar 1, 2019

Try cutting open one of your old fuel filters. Is it full of what feels like slime..? If the answer is yes you have an algae problem.

DMiller · Mar 1, 2019

Nasty when it arrives, hard to correct and takes effort with tank cleanings, filter and lines flushes, just NASTY!

kshansen · Mar 1, 2019

Not sure why it seems to affect one machine and not others, could be due to the venting or some other design difference in the one machine.

About the only place we had the problem was a tow-behind air compressor. I sure the problem with that one is the fact it was not used very much and would sit unused for weeks or months at a time!

If steaming the tank out I would try to come up with some way to dry it out after, maybe use a heat gun stuck down the filer pipe for a day? Then dose it at the maximum amount of the algecide for a few tankfuls of fuel and change filters often.

JD955SC · Mar 2, 2019

I have seen it as a brown slime on top of fuel and as chunks and particles inside fuel filter.

It’s one of the first things I check if a machine is having fuel issues. I pull the filters and dump out and cut open the old ones to see what I find and then look into the tank.

Typically see it in fuel that sits around a while. Frequent use machines with fresh fuel supply typically don’t see this issue.

Nige · Mar 2, 2019

Thinking about it cleaning the tank is only one step (and probably the first) to take, but when there is a fuel return line pumping excess fuel back from the engine to the tank, dosing the system with algicide appears to be the only definite solution otherwise the algae will just propagate back to the tank mixed with the retuning fuel from the engine and the fuel linesl.

Rob Marshall · Mar 3, 2019

Nige said:
Thinking about it cleaning the tank is only one step (and probably the first) to take, but when there is a fuel return line pumping excess fuel back from the engine to the tank, dosing the system with algicide appears to be the only definite solution otherwise the algae will just propagate back to the tank mixed with the retuning fuel from the engine and the fuel linesl.

We tested for algea . It came back negative. We still treated the tank for it to be save . Now we are thinking it might be the fuel separating due to the return coming back so hot. I believe they call this asphalting?

heymccall · Mar 3, 2019

Throwing code, yet no code # or real description?
D6K, but, no serial # prefix even?

What about screen in supply port?

Rob Marshall · Mar 4, 2019

heymccall said:
Throwing code, yet no code # or real description?
D6K, but, no serial # prefix even?

What about screen in supply port?

Throws low fuel rail pressure code. Don’t see any screen . Tank has blackish coating in it and I tested for algea came back negative . To be sure still shocked the tank and didn’t change anything.

Rob Marshall · Mar 4, 2019

Rob Marshall said:
Throws low fuel rail pressure code. Don’t see any screen . Tank has blackish coating in it and I tested for algea came back negative . To be sure still shocked the tank and didn’t change anything.

I see the screen on the sheet you sent is that screen the one where you fill it?

Nige · Mar 4, 2019

Nope, it's one of the fittings on the 277-5191 fuel pump. The pump is #17 on the illustration below. Unfortunately when you go to the list of parts available for the pump there is no illustration. Hopefully HMC can point out for you exactly which one it is.

Nige · Mar 5, 2019

Sorry, should have read HMC's post more carefully. The fitting on the inlet side of the fuel pump where the fuel line enters the pump from the tank has a 2720610 screen inside it.

Rob Marshall · Mar 5, 2019

Cat says there is no screen ?

heymccall · Mar 5, 2019

Rob Marshall said:
Cat says there is no screen ?

Still haven't seen a serial number.

2012 D6K Fuel System Problem

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