73.5 help with fuel return line please

[rockreid]

Hi. I ordered a fuel return line part# 911 356 064 05 for my 73.5 CIS 911 Targa restoration project. I am a little confused as to how this should look attaching to the engine. I am assembling this car rather blind with only online parts diagrams and forum research. Does anyone have a photo of this fuel line properly installed? Thanks for any help.

[ossiblue]

Sorry, no picture but this will help: 911 CIS Primer - Fuel Hoses

The diagram is for a 73.5 CIS, like yours, that has the throttle positioning valve that is part of the return line. You will not have a return line from your accumulator, however, and neither does the diagram.

Basically, start at the fuel distributor return port. A short line runs to the cold start valve and a long line runs across the engine to the return tube in the chassis frame, by the fuel filter/accumulator. There it a "T" fitting in this line where a return line from your throttle position valve and the line from the WUR will enter. Hope this helps.

[E Sully]

I looked up that part, and it is unfortunately incorrect for CIS, it is for MFI engines. The 73.5 CIS parts are listed in the PET as 911 T-K.

[E Sully]

The fabric covered lines off the engine can probably be purchased and cut to fit.
Unfortunately, the '73 CIS Engine compartment metal to hose return line that connects to the metal line in the tunnel, #5, is NLA.
In the pictures, I labeled the lines for you, but #5 in the second picture would have to be fabricated.
You might be able to contact member Len Pelican Parts Technical BBS - View Profile: BoxsterGT to see if he can make it up.

[BoxsterGT]

I just came across this (thank you Ed) and it confuses me a bit.

#1 looks like black Polyamid, and the rest looks like the old cloth covered hose. I was told for low-pressure returns on all the 73.5 & 74 CIS models Porsche used the cloth covered hose with clamps and a double Tee made of plastic. The confusing part is the Polyamid tube for #1, unless its mated to a later model FD.

The 73 models are the last to use steel tube through the tunnel. The 74 models were fitted with white nylon tube which turned out to be a big mistake.

For the 75 911 Porsche went to polyamide lines through the tunnel with rubber hose at each end. Since the pump was rear mounted, most of the system is low pressure so the rubber hose & Norma clamps were adequate. From the pump up to the accumulator (high pressure) they went to Polyamid once again. And of course Polyamid from the accumulator to the FD.

I have the correct E-85 rated hose and Norma clamps in stock if you want to do this work yourself. For the Polyamid tube, I can send this to you or assemble it to your specific needs.

Please, for questions email me only. No pm's, no PM's, NO PM's.

Len at Autosportengineering dot com

[rpc356]

Originally Posted by BoxsterGT

I just came across this (thank you Ed) and it confuses me a bit.

#1 looks like black Polyamid, and the rest looks like the old cloth covered hose. I was told for low-pressure returns on all the 73.5 & 74 CIS models Porsche used the cloth covered hose with clamps and a double Tee made of plastic. The confusing part is the Polyamid tube for #1, unless its mated to a later model FD.

Len, that is definitely a cloth covered hose, not Polyamid.

[BoxsterGT]

Ooops! My bad.

I was identifying the black Poly line next to the 1, and not the yellow enhanced hose a bit further over.

I get confused easily.

Len

[E Sully]

It is a very simple low pressure return line. 5 is a metal tube with a few bends to contour to the chassis clamped to line 4, then crimped to a fabric line when it is out of the engine compartment that attaches to the metal return line at tunnel by clamp. You can buy some tubing and make it yourself using clamps instead of the factory crimp.

[rpc356]

Originally Posted by BoxsterGT

Ooops! My bad.

I was identifying the black Poly line next to the 1, and not the yellow enhanced hose a bit further over.

I get confused easily.

Len

It's hard to keep things straight, there were so many changes from (mid)year to year, especially in the longhood years.

[BoxsterGT]

Here is the best replacement fuel Hose you can buy for a early Porsche..........





It is E-85 rated and available in bulk or cut to length or as a hose assembly. Above is a set for a 73.5 Fuel Feed hose assy.

Len at Autosportengineering dot com

[BoxsterGT]

Thought I would bring this up to date, as a lot has changed over all these years.

In the post above you can see the Fuel Feed and Return Hoses & Lines are multiple-piece. They run through the Drivers side rear frame rail, and use Norma hose clamps to hold them together.

Porsche has done this with most all of their early models.

However, Clamps have their limitations with the higher pressures of fuel injection, and from Model Year 1974, all Porsche models come with fuel injection.

Recent news from our host is that the "side outlet" Fuel Pump of the 73 > 76 Porsche 911 has dramatically increased in price and is now just under $800.

Just a year or two back, the cost was half this amount, and this was still hard on the wallet. A fellow Pelican member with a 74 Carrera wanted to find a replacement pump, but still keep it a Porsche issued part. And so we looked for an alternative.

It just happens that the 930 has (2) "Flow-Through" pumps, and the rear is located just where the 74 Carrera model has its pump. So, we looked up the hose layout for the 930 and made up a similar fuel line to use on the 74 Carrera......



It also happens that the blend of Ethanol in today's fuels makes it necessary to use a more durable E-85 Rated hose, and we now have the benefit of a lower cost Pump and a more durable E-85 Rated Hose.

However, the most important benefit of this change, is that by re-routing the Feed Hose to above the Rear crossmember we are able to make this a One-Piece CRIMPED hose from Pump to Accumulator.

This eliminates the need for hose clamps. With the possibility of 100 psi in the system if a return line became blocked, the crimped hose reduces the risk of fire, especially in the engine compartment.

The benefit of Fire safety alone make this worthwhile, with the added benefit of longer Hose life and the lower cost of the pump, this is an easy decision to make.

I hope this helps.

Len.Cummings at verizon.net

[BoxsterGT]

And yes,

the 74 Carrera above has my E-85 Rated Fuel Hose and Polyamide Tunnel Lines.

Len

[Montucky]

Hi len,

Have sent you multiple emails for the past couple of weeks trying to get ahold of ya for making some fuel lines. Any issues with emails lately?

[BoxsterGT]

Montucky-

This Pelican link does not seem to work as I have tried to pm you through this link.

E mail me the normal way- Len.Cummings at verizon.net

Thanks

Len