el jefe

Here's what I am faced with. This is the fix that a lot of 928 owners are performing, by far the most popular and inexpensive route. Take some high pressure 30R9 fuel injection hose (7.5mm pressure side; 9.5mm return side), a couple of 14mm and 15mm ABA fuel injection clamps and off you go. Well, not so simple it seems as this is a subject causing more controversy and theories since the "who shot JR" debacle of the 80's. 
I was faced with many options tried and trued by many enthusiasts each one with pros and cons so on and so forth. The option you see above really didn't sit well with me, I like to replicate the factory look as much as I can instead of the shade tree solution. This one has gone the distance so far. You can opt for custom AN braided racing style lines and fittings (the superior more expensive method), make your own factory hose by inserting nylon fuel injection hose into high pressure hose, or take the lot to a hydraulic hose manufacturer and have them crimp on ferrules over the hoses and fittings. I think I'll go with the last option.
This is what the original factory version high pressure line looks like. This one happens to be the one that screws into the fuel filter in front of the right rear wheel. Notice the collars around the end, as you can see they aren't crimped. As it turns out the pressure lines have barbed ends that are "pressed" into the line and since the inner lining of this particular fuel line is made of nylon/ptfe/plastic (not sure which), they bite in and create a superior seal. The logic behind so many debates on the subject seems to stem around the fact that you mustn't clamp/crimp anything over a rubber line with a rubber inner over a barbed fitting. I buy this logic because it seems to make sense especially if it was manufactured in this way.
Here is what the barb inside the high pressure line looks like minus the 17mm hex fitting. As you clamp it down, so the logic goes, the barbs cut into the hose. The exterior collar is there to protect the ending. (image borrowed from Belmetric.
This is the return line. The metal end is the line coming from the engine bay via the undercarriage and the rubber bit goes directly into the fuel level sender. The rubber line was fraying at the ends (nylon cords and all) so it was a candidate for replacement. Here is an example of a barbed end with a single barb and a smooth surface between it and the collar on the line. I cut of the crimped fitting that was holding it in place to remove the line, so in this case I'll probably use an Oetiker high pressure clamp fitting upon replacement with a fresh line. To replace the original Cohline ferrule, a special press that costs about what I paid for the car is needed so that idea was nixed, and yes I was thinking about buying it.
Here is the end of the return line going to the sender with the hose off. Now I thought about buying this entire line (part # 928 356 031 01) from Mike at Porsche for under $140 but when I looked at how this line attaches to the undercarriage with the line clamps that seem to be secured with bent metal ears I opted to not incur any more work than I already had. Bending 34 year old metal tabs that have been exposed to mother nature and road salt would surely mean breakage...then I'd have to bore you with how I rigged up a clever way to reattach the clamps without the tabs. 
This is the only rubber fitting an the return line mentioned above.
The Oetiker high pressure fuel clamp...
And the Oetiker 1099 knipex dual purpose (for front and side crimping in tight spots) pliers to crimp it in place. German tools for a German machine, what could be better?


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