Fuel Lines – Do they really need to be replaced?

Changing Fuel lines > is it really Necessary?

Toyota and many of the major manufacturers recommend replacing the high pressure fuel lines between the rail and the injectors at certain intervals. Many of these manufacturers actually claim one time use.
BDG not happy to just ‘waste’ money if not really required went after the facts. With no real information on the internet, we put our R+D team to work. What they came back with was quite interesting.
So what have we learnt?

Claim #1: 1 Time use only because they won’t seal
In our own lab, we grabbed a brand new line set and tested them until failure. Essentially loosening and re-tightening. First time, pulled up really well, as did the second. By the third time, tightening torque was reached before the same rotation degree was reached (went tight) , fourth time, tight with nearly no rotation angle.
RESULT: Definitely fine for 2 times ‘round, 3 maybe, 4 definitely not.

Claim #2: The lines Erode

This is probably the most concerning. From all the used lines returned, there was a point from 100-120 thousand Kms that the flanged sections just before the injectors started to erode really quite badly. Please keep in mind that any material that breaks off here is sent directly through the injectors as this is after all the filtration that there is…
The below photo shows a fuel line out of a Hilux 1KD 2007 model, this line has only 140,000Kms. You can clearly see that there is a shiny polished finish above and below the recessed area, however where the ‘recessed’ area is, you can see where the surface has been eroded away. No prizes for guessing where this went!

What’s BDG’s recommendation?
Our real world testing has shown that these lines should be replaced every 100,000kms or so to be on the safe side, however they are ok to reuse at least once during this period. This is very different from current thinking:

So working with Toyota’s recommendation of one time fit only, it’s been seen that a car has had over 160,000+kms that has never had lines removed and therefore still has the original lines fitted. However a car that might have had tappets done and therefore removed + replaced the lines only 20,000kms ago, is now up for a new set of lines again because of the need of injectors.

Again, this is all in a perfect world scenario. Lines that have been bent overly heated or otherwise probably should be replaced as a matter of caution…

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