help with fuel lines for 73.5 CIS plz

[rockreid]

I have done extensive research on this forum regarding how to run the fuel lines for my project 73.5 CIS Targa. I have looked at pics and diagrams posted here but one thing is very confusing. My fuel distributor has 3 bottom outlets and all references here show just 2 fuel lines on the low pressure side.. one going to the 4-way plastic connector and the other to the cold start injector.


I have 3 outlets on my distributor... where do they go?






th



Also, there is a longer plastic nozzle under the airbox..is this the vacuum source for the distributor (spark)?

[E Sully]

The fuel distributor has an inlet from the fuel pump, a line to the cold start valve, a return line off the pressure regulating valve, and the control pressure line is on top, which goes to the TPS and WUR. The fuel distributor return line joins to the control pressure return lines after the WUR and Throttle position valve.
What model fuel distributor do you have? 0 438 100 004 is the original type. Yours seems to be a later type.
The line on the bottom of the air box may be the oil drip tube that drains off the front of the engine between the oil cooler and clutch.
The line to the distributor comes off the throttle body.

[rockreid]

my fuel distributor is part # 0 438 100 017

initial research shows it may be for 1974 911. I am still at a loss as to why the right outlet has a dual banjo fitting and the left is a nozzle to accept a clamped hose resulting in 3 ports.

[rockreid]

thanks for the tip on the bottom nozzle for the oil catch tube. But my fuel distributor situation is as confused as ever. Hours of research on this forum, the online CIS handbooks and FAQ's, and internet have told me nothing on the correct line routing for my particular CIS. The part number 0438100017 keeps turning up as for a 74 2.7, not my 2.4T CIS. But since this was an evolving ime for Porsche, my fuel system may be stock. I have no idea.
I did call Bosch Techline and they couldn't help since this part# is too old.

[E Sully]

I'll look into it, take a few pictures, and get back to you.

[rockreid]

I'm going with option A... it stands to reason looking at the diagrams and scratching my stubble thinking about it that the right hand dual banjo fitting is for both the delivery from the fuel tank and to feed the CSV. Both of those connections are now there.

The left hand barbed single fitting is the return to the 4-way junction back to the tank. I'm going with that for now. Now way to know for sure until I get my body back from paint. Thanks for the help.

[E Sully]

That should be correct. I looked up the fuel distributor and it is listed for a 1973.
The fittings are an updated later style than the original. First picture is my original 73 fuel distributor, second is a 2.7 with the later fittings similar to yours.

[AlexGross]

Check out this site:
911 CIS Primer - Fuel Hoses

I posted a link to this site in a thread a couple of days ago:
Excellent CIS Information & Troubleshooting Resource

Jim has put together an incredible resource for CIS troubleshooting--there are diagrams, component descriptions, etc. Enough info to help you solve all of your CIS woes.

Here is one of the many diagrams from the site:


There are accompanying descriptions and legends for each diagram.

Hope this helps you out

Cheers,

Alex

[rockreid]

Originally Posted by E Sully

That should be correct. I looked up the fuel distributor and it is listed for a 1973.
The fittings are an updated later style than the original. First picture is my original 73 fuel distributor, second is a 2.7 with the later fittings similar to yours.

OK, car is running and driving however I think I may have a hot engine /boiling fuel/low fuel pressure issue due to my updated 017 FD plumbing. In the 004 fuel line routing in the top picture, the CSV is connected on the same side as the Fuel Return out of the FD. However, in the 017 (lower picture) installled in my car the CSV is connected to the side with the Fuel In from the fuel pump using a 90deg barb fitting. Is there a pressure difference between the Inlet and Return sides of the 017 FD? If so, could this be a reason for the engine stalling when the engine is hot?

[boyt911sc]

Originally Posted by rockreid

OK, car is running and driving however I think I may have a hot engine /boiling fuel/low fuel pressure issue due to my updated 017 FD plumbing. In the 004 fuel line routing in the top picture, the CSV is connected on the same side as the Fuel Return out of the FD. However, in the 017 (lower picture) installled in my car the CSV is connected to the side with the Fuel In from the fuel pump using a 90deg barb fitting. Is there a pressure difference between the Inlet and Return sides of the 017 FD? If so, could this be a reason for the engine stalling when the engine is hot?

rockreid,

The CSV is both connected to the main fuel delivery line from the FP for the above FD's. Are you sure you have FD 0-438-100-017? This is not the right FD for your engine. The inlet pressure is higher and the outlet pressure is the low pressure for the return fuel. This is applicable to all Bosch fuel distributors 0-438-100-xxx configuration used in CIS. You have mis-interpreted the FD configuration for FD-004. The CSV could not be supplied by the return line because the CSV needs high pressure fuel (system).

Do you know your system and control fuel pressures? The problem you are having is not attributed to the pressure differential of the FD but rather to the system and control pressures. Please post the numbers for the fuel pressures. Thanks.

Tony

[rockreid]

ambient temp : 65 deg F
WUR resistance : 20.2 ohm

System Pressure : 42psi (3 Bar)

Cold Control : 24psi (1.7 Bar)

Warm Pressure : 42psi (3 Bar)

Time Delta for Warm Pressure : 3 minutes to 3 Bar

Residual Pressure:
5 min : 20psi (1.4 Bar)
10 min : 10psi (0.6 Bar)
15 min : 8 psi (0.5 Bar)
30 Min : 0 psi/ Obar

this is the FD in my 73.5 I don't not know the history of how or why this FD is in my car.



this is the fuel line configuration in my car and I don't know if it is correct. The Fuel Pump and CSV are connected to the 90deg barb on the right. The Fuel Return is the single barb on the left.:



The potential problem I see is that the fuel pressure supplied to the CSV using the same 90deg fitting as the fuel pump supply into the FD... wouldn't that be returned to the fuel tank immediately via the CSV and lower fuel pump pressure into the FD?

[boyt911sc]

Rockreid,

What is the WUR you are using now with the TPR (throttle pressure regulator)? How did you measure the control and system fuel pressures? Keep us posted. Thanks.

Tony

[rockreid]

I seem to have a 001 WUR that appears to be working according to my fuel pressure readings. I'm not sure which TPS I have but I imagine it is stock along with the CSV



My issue remains I don't see how the 017 FD on my car can be supplied the correct fuel pressure as presently connected to the CSV, since from the diagrams it looks like the return out of the CSV is connected to all the other return lines via the 4-way splitter connector. I wonder if that plugged Outlet on my 017 can be used to supply the CSV and only have the fuel pump connected to the Inlet by itself.

[boyt911sc]

Rockreid,

Forget about the fuel lines connections in your engine. There is nothing wrong with them and the CSV connection is not the problem. The root cause of your problem is the fuel distributor. Take a close look at your fuel pressures. That is where the problem lies. Keep us posted.

Tony

[rockreid]

I already had my 017 fuel distributor rebuilt last year. I am thinking I should just go ahead and swap out my present FD and get the 004 most other 73.5's use. I am thinking some mechanic back in the 80's switched out the original FD for some reason and this car hasn't run correctly since. The previous owner disassembled the entire car sometime around 1988 because he wanted to rebuild the engine (he vaguely said it wasn't running right) and restore the body. He never did.

I did 25 years later. Now I just want to verify my car needs the 004.