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Know your Supply Tubes

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Know your supply tubes

Internally contained in the Supply tube is the Edge Filter. The Edge Filter is a safety feature, built into the supply tube. It is designed to break particles larger than 50 µm into smaller pieces to avoid major malfunctions like continuous injection, blocked nozzle holes, amongst other things that can cause catastrophic engine failure. Contamination smaller than 50 µm will still cause damage to your injectors and reduce their lifetime. Careful inspection of the edge filters will tell you about your fuel quality and filtration system.

If your supply tubes look like new:


Indicates the good quality of fuel that you use, with a proper fuel filter and proper filter interval changes.

If you have slight wear traces on it:


This tells you that you get a lot of particles in your injectors and you should change your fuel filter more often.

Flow channels built on the edge filter:


You have serious problems with your fuel quality. You should change the location where you buy your fuel. Often times the dirt gets into the fuel at the petrol station, by having leakage allowing dust into their fuel tanks. Or you do not use the correct filter for your application or change your fuel filter often enough.

Many people think that an older fuel filter will filter more than a new one, because the orifices on the filter material are getting closed or smaller, but that is simply wrong. An older filter will reduce the flow through it, which causes a bigger pressure resistance of the filter and a bigger delta pressure between the inlet and the outlet of the filter. This leads to the fact that bigger particles are getting pressed through the filter material and the effectiveness of filter is getting lower and lower and the number of particles getting to your injectors is increased.

In order to inspect your edge filter, it must be pressed out of the inlet end. Once removed, both the supply tube & edge filter are NOT reuseable !


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Those are great pics! If a person doesn't understand this 'illustration' then it will be hard to explain it any better.... Any idea how much dirt / water it takes to cause the two problems above? How many miles were on these?

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Thank you Dan!

I am not aware of the mileage on these examples. I would like to know. This makes one think about the quality of the fuel and the filtration one is using and makes one want to change filters at a safe interval, doesn't it?

Here is an interesting bit of info about connector tubes that people ask about. And that is the differences between the tubes for the 5.9 and the tubes for the 6.7 and the fact that the newer tubes are now different.

Here is the scoop as I know it. The newer tubes are designed to replace both the 5.9 tubes and the earlier 6.7 tubes. There is only one part # available now. That is, unless somebody has some old stock available. Also there are some Chinese copies out there that I will recommend one to stay far away from.

Early 6.7 tubes will NOT work in the 5.9 injectors and vice versa. The “new” tubes work in both. So there was, at times, 3 different part #’s in addition to the Chinese copies. Grab the new part # and you are good to go. :thumbup:

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This is really good info to have, thanks so much!

I can't imagine using anything chinese in an injection system!! Most of their stuff is damaged just taking it out of the package!! I would also think if you used their junk connector tubes that they would actually be putting debris into your injectors. Not good at all!!! (The 5.9L Common Rail 'only' ran up to about 20,000 psi of injection pressure. But you still want a very clean and debris free fuel supplied to this system or you will have catastrophic failure and usually quite quickly. The newer engines are operating at even higher pressures so it is just that much more important to have micron clean fuel!!) (Oh, and just a reminder: the old 12V VE pumps injected fuel under 5,000 psi. So you can see that the trend is to higher pressures. Higher pressures mean closer tolerances and that is why the fuel must be kept cleaner!)

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