As I'm doing a bunch of work on my 74, I decided to replace the original
plastic fuel lines with some stainless lines. I am amazed that these
plastic lines are still working and that they hadn't cracked given their age.
The plastic lines seemed kind of hard but I didn't think much about it
other than I never really liked them.

So I get everything loose and get ready to pull the lines and had to pop
the plastic lines out of the plastic keepers on the firewall, and CRACK,
the return line shattered and cracked right where the line starts to go up
towards the engine shelf.

After I pulled the lines, I carefully examined them and noticed that the plastic
inside the tunnel seemed to still be soft and bendable; however, the plastic
beyond the firewall in the engine compartment was very hard and the closer
you get towards the corner were the heater tube is, the more brittle the lines
get.
In my situation, the more brittle line was actually the return line which would
be the absolute worse line to break since the pump would continue to pump
fuel even after the line broke.

Anyway, I have attached some photos showing what I noticed.
I am now a believer like Clay in removing and getting rid of those plastic lines.
At this point I question why anyone would continue to use the stock factory lines.
It is only a matter of time before they cause a problem.
Luckily for me, the break happened while I was actually replacing the lines.

--------------------------------------------
A few notes on Clays Technical Article:

It would be useful to tell/show folks the 2 places where the lines are
attached inside the tunnel. One is under the shifter, the other is directly
under where the wire harness enters the cabin just in front of the
access panel by the firewall. Both of these need to be loosened
before the lines can be removed and its not particularly easy to do.

One tip I learned is to make sure that both ends of each line is open and blow some
compressed air through them PRIOR to removal. This will ensure that there is
no remaining fuel in the lines to spill inside the tunnel. - Guess how I figured out this one.....

Another tip that I've read about and intend on doing relates
to if there is concern about rattling of the lines.
The tip is to slip the tubing through heat shrink tubing has you install the
lines. Nice and simple and should be effective.

--- bill

Autopsy Pictures follow:

Click to view attachment
Click to view attachment

Crap. I almost wish I hadn't see this. I was just about to replace all my fuel lines EXCEPT for the the plastic ones. That is, until I saw this. I now feel that it would be wise to go ahead and order the stainless steel set. Waiting to hear back from the folks at Tangerine as to whether the 7mm rubber lines I just paid for will fit over the stainless lines. That sound you hear is the sound of more $$$ leaving my bank account...

I agree in changing out the lines. Mine were the same as yours. I was amazed on how well they stood up inside the tunnel but the rest were really bad. Mine started leaking just a tiny bit under the tank, so I just replace everything 100 %. My natural gas furnace is in my garage so the last thing I want is a 914 bomb in there. I sure sleep better now.

Eddy

Replacing 30+ year old plastic fuel line w/Tangerine Racing SS should be a "no-brainer". Trying to get just one more summer out of my 914 before a major "refurbishment", I had one of those plastic lines crack. Luckily, the failure occured in my driveway, just after start-up, so I was able to attend to things before I was on the road with my engine temps up!

I just replace my lines a couple weeks ago and found the same problem as well as no clamps on the fuel hoses under the tank!

Chris Foley's stainless lines are great and they only took me about an hour to install with the engine in the car!

I agree everyone should seriously consider this upgrade as the stock lines are just an accident waiting to happen.

Why don't they have a flare on the metal part at the end of the nylon lines? Whose idea was it to use that stuff anyway, is it that much cheaper than steel? I just pulled them out when I went to Ceres to help them out, came out easy, SS lines went in pretty easy too.