MFI fuel line replacement question

[David E. Clark]

I'm looking for the fuel line in the engine compartment that runs from the tank to the fuel filter. Here is a picture of mine:



As you can see, this one has seen better days. I'm looking to replace it but I'm having trouble locating the correct part. I believe this is the correct part - part # 901 108 051 06 (page 126) - but I'm not certain. If this is the correct part, can it be duplicated with high pressure fuel line and a T- fitting? $154.50 is quite a bit more than I was expecting! I'm thinking that a few feet of 3/8 (don't shoot me for thinking SAE) or 10mm fuel line and a T-fitting would be less than 1/10 the cost and I can't see any reason off the top of my head why it won't work. I know that is not the way if came from the factory but no concours judge will ever be looking under my car! Any advice appreciated. Thanks, David

[Zeke]

There is no reason not to use metric fuel injection rated hose and FI rated "norma" clamps. Just save the tee and look for the restrictor that has been mentioned many times. It should be in the return line, but I don't know which one that is in your pic.

[David E. Clark]

Thanks Milt. After reading your post I did a little more searching and found this thread which answers my question and provides loads of information about MFI fuel lines in general. Don't know how I missed it in my first search but when you reminded me about the restrictor I added that word and there it was. Much appreciated!

[Grady Clay]

David,

Good, you found the best thread.
Braided Fuel Hose for a 72T MFI
Braided Fuel Hose for a 72T MFI

Does your hose assembly have the ‘restrictor’ inside the hose? If so, what are the dimensions? Can you confirm the hose length measurements on the prior thread?

Are you going the route of installing crimp ferrules at the ‘tee’? If so, can you find original appearing parts and crimp?



Milt, my friend, the reason for using the Norma-Schellen pinch-type hose clamps is safety.

The standard braided hose used on our MFI cars was originally designed for 3 psi carburetors. Use on our 11.8 ±3.0 psi MFI system puts the hose and connections closer to the limit. Failure in hose systems are most common at the junction between the hose and fitting. With hose-to-barb fittings on our MFI, the choice of clamp is a very important part of the system.

Norma-Schellen made OE clamps for Porsche that were sized to the millimeter for the hose. Most of our MFI clamps are 12 mm to fit the 7 mm hose. This clamp puts remarkably equal pressure around the hose and doesn’t tend to damage the hose. You will find many N-S clamps around a Porsche that are various sizes including 13 mm, which is not appropriate for the fuel hoses.

Yes, there are other pinch-type hose clamps. Yes, probably some will work as well as the OE clamps – if size and design are correct.

In my opinion, no one should use the worm-screw type hose clamp in this application. These clamps don’t apply equal pressure around the hose. Most important, these clamps damage the hose cover. Some cheep clamps won’t stay tight.

Given the extreme danger of leaking fuel, I choose to use the best systems. For an original appearing system, all OEM parts are best. Yes, there are better components and systems. In the appropriate application (vintage racing), I would only use screw-together Aeroquip (Russell, etc.) aluminum fittings and the matching steel braid hose. I would also use a ‘Fire sleeve’ covering for insulation and fire safety.

Best,
Grady

[David E. Clark]

Originally Posted by Grady Clay

Does your hose assembly have the ‘restrictor’ inside the hose?

Nope! I cut apart every inch so I am quite sure that I didn't miss it. It was pretty easy since all of the hose was dry rotted - it's amazing I didn't have a fuel leak! I am long from the first owner so I can't say for certain that my assembly is a Porsche factory part but by the looks of it, and comparing it to the ones pictured here and here, I'm guessing it is original. There are no markings on any of the crimp fittings, the "T" fitting or the hard lines.

Have you ever seen one of these restrictors? Do they really exist?

Originally Posted by Grady Clay

Can you confirm the hose length measurements on the prior thread?

The hose lengths from my setup are 6" (152mm), top right in the picture I posted above, 5.6" (143mm), top left in the picture I posted above, and 13" (331mm), bottom hose in the picture I posted above. 10.5mm outer diameter. 7mm inner diameter.

Originally Posted by Grady Clay

Are you going the route of installing crimp ferrules at the ‘tee’?

I am not going original looking. I cut out the "T" fitting and hard lines and I am buying original style cloth braided fuel injected rated replacement hose and using Ideal clamps. I've used these before without complaint. They seem well made to me and I have plenty of them laying around.

Any comment on whether my proposed fix is adequate. Is this a situation where I should have the local speed shop rig up a replacement using steel braided hose like Len did here or original style hose like Howard did here? That would still probably be less expensive that the factory part. All your warnings about fuel leaks sure got my notice!

Thanks,

David