1974 911S CIS Problems/Questions

[Glen Pettigrew]

Would like help with 1974 911 with completely stock 1974 '911S' engine.
Original non 'S' engine has pulled head studs.
purchased a wrecked 911S and put the engine in my car.
No history of 'S' engine available but, cold compression
on all 6 cylinders was about 145-155. All head bolts moved
very little while re-torqueing them.
I replaced flywheel seal, Oil cooler seals, Oil breather seal etc.
adjusted valves and new silicon gaskets. (although valve covers
still appear to be leaking, will work on that later..)
new cap rotor and points (still old wires, will order soon)
Had bosch platnum plugs that looked excellent/ near new.
replaced everything rubber on CIS including injector seals
(but,not the hard fuel lines or internals of fuel distributor).
replaced air box (was cracked wide open, had pop-off valve but,
was missing drivers side mount. suspect crash caused it to break).
Checked injector spray pattern on all injectors and they look fine.

Symptoms:

Engine hard to start when cold (feels/sounds lean). (haven't check
CSV yet) not too concerned with this for now.
Once running, idles fine and steady.
When accelerating, feels hesitant during the 2100 - 3000 range
in 1,2 & 3 gears. Pulls smooth in 4 & 5th gears.
Engine seems to run great below 2100 and above 3000 RPM.
timing is set corrrect. Measured/adjusted mixture, CO at idle is 1.3
(label on alternator cover says 1.0 - 2.5 . Not much use in going any further until
I can fix what I guess is a CIS problem.

I am attempting to do CIS checks and am having a problem understanding
the procedure in the service manual.
On the fuel distributor port for control pressure I have two
lines connected, one goes to the WUR & the other (with banjo connector)
goes to throttle position regulator. I connected the end of the
'T' without the valve to the fuel distributor leaving the throttle position
connection on the fuel distributor (IS this correct?) I understand the other
end of the 'T' with valve connects to the line removed from the fuel distributor
going to the WUR.

Assuming I have connected the guage correctly....
completely cold engine (sat over night)
temperature approx 10C / 50 F
WUR Bosch P/N 0438.140.001 (no vacuum connection present)

These are the numbers I get:

Step 1:
fuel delivery coming out of fuel filter;
~ 1.2 liters in 30 sec.

Step 2:
fuel pressure at fuel distributor without WUR or throttle position regulator
connected;
5.8 BAR / 85 PSI

Step 3:
fuel pressure at fuel distributor with only throttle position regulator
connected: (valve on line going to WUR closed)
a. 3.3 BAR / 47 PSI (throttle at idle)
b. 4.2 BAR / 61 PSI (throttle at mid point/max pressure)
c. 3.1 BAR / 45 PSI (throttle wide open)

Step 4:
Valve open on line going to WUR (power wire disconnected)
a. 2.2 BAR / 32 PSI (throttle at idle)

Step 5:
Valve open on line going to WUR (12v applied to WUR)
a. 2.7 BAR / 39 PSI (after 5 min, throttle still at idle)
b. 2.8 BAR / 41 PSI (after 6 min, throttle still at idle)
c. 2.9 BAR / 42 PSI (after 7 min, throttle still at idle)
d. 3.0 BAR / 43 PSI (after 10 min, throttle still at idle)
e. 3.2 BAR / 46 PSI (after 10 min. throttle at mid point)
f. 2.9 BAR / 42 PSI (after 10 min. throttle at wide open)

My conclusions:
Step 1. = Fuel delivery is fine.
Step 2. If this is "System Pressure" it is too high.
should be 4.5 - 5.2 BAR.
Step 3. If part a. is system pressure it is too low.
Step 4. According to chart, at 10 C, should be between
1.4 BAR and 1.8 BAR therefore it is too high.
Step 5. part d s/b 2.8 - 3.0 BAR (good)
part e s/b 3.4 - 3.8 BAR (too low)
part f s/b 2.6 - 3.0 BAR (good)
My guess is: I need to adjust pressure relief valve in fuel distributor.
I don't know what to do about throttle position regulator.
Book says to check at "partial throttle" I checked at the
position which gave the highest pressure and it looked
like mid-point in the travel.


Any advice would be appreciated.

Thanks much..
Glen Pettigrew

[retrogarage]

Another thing that causes high fuel pressures is a blocked return lin to tank. Same symptoms as pressure regulator on back of fuel distributor. Ask me how I know.
I undid front fitting to tank. Unscrew fitting on back of fuel distributor. Unscrew fitting going to accumulator and plug with finger. Put air hose into hose that you unscrewed from back of fuel distributor and blow junk from engine towards tank out of the line.
You dont want to blow it towards engine.

Oh yeah how is your WUR?

[ossiblue]

Glen,

Boy, you are thorough! So much so, that I got a bit lost without pictures--seriously!

You are correct on which end of the gauge to connect to the fuel distributor and which to connect to the wur. However, I've always connected the gauge directly to the line from the distributor to the wur, not from the throttle positioner port. I honestly don't know what effect, if any, your connection will make on the pressures measured. You might try the straight connection from FD to wur (through the gauge set, of course) and see what you get. Be sure to report back your findings, if you do.

Now, from my limited experience only, here's how I see your numbers.
Step 1. Agree, looks fine

Step 2. Agree, seems too high but this may be due to your connection to the distributor--someone who is more expert will chime in, I'm sure. Also, as long as the pressures can be regulated, this may not be a factor. Or it may be as retrogarage posted--blocked return.

Step 3. Can't comment, I've never run that test.

Step 4. Agree.

Step 5. Agree.

IRCC, your 74 does not have an adjustable wur--at least not like the later, "tap the plug wur's.

I don't know if my comments have helped because I'm unfamiliar with the wur on a 74, but it is another perspective on your problem that may prompt someone who can offer direct help to respond.

[Glen Pettigrew]

Retrogarage:

Thanks much for the suggestion.

I Removed the Fuel Return Line as shown in the second picture.
With Fuel pump running, lots of gas came out of the Fuel hose
shown. The rubber line between the hard line and the fuel distributor
is all new. But, while it was removed, I did put about 80lbs pressure to
the hard line which goes to the tank, Heard lots of bubbles coming
from the tank. (I assume this means the return line is not blocked
in my case). So far I don't see anything to suggest a problem with
the WUR.

L.J.:

1st picture shows close-up of Fuel Distributor.

Normally, The WUR line connects to the Fuel Distributor
through the Banjo fitting for the Throttle Position Regulator.

The WUR line has been removed and connected to the Guages 'T'
Line with the valve (as seen in the second picture.
The question I have is:
Should I close the valve and measure the 'System Pressure'
as shown in the second picture? If so, wouldn't the 'Throttle
Position Regulator' cause a false reduction in actual
'System Pressure'?

If I remove the Banjo fitting that goes to the 'Throttle
Position Regulator' and connect the guage directly to the
Fuel Distributor port shown, is that the real 'System Pressure'?

Thanks much for the suggestion!
Hope this helps clarify what my basic question is:
How is 'System Pressure' measured?

Glen Pettigrew

[Glen Pettigrew]

Whoops, forgot to attach pictures....
Here they are:

[ossiblue]

Glen,

Your second picture shows the set up I've always used to set/measure fuel pressures. By closing the valve, you would be reading the system pressure. On my CIS cars, the port you show in picture 2 (attached to the gauge), is the one that normally connects directly to the wur. Admittedly, my 73.5T has a 76 2.7L engine so I'm not familiar with the plumbing of the earliest CIS like yours.

You posted, "Normally, The WUR line connects to the Fuel Distributor
through the Banjo fitting for the Throttle Position Regulator". I've not seen that. Out of curiosity, what, then is connected to the port shown in picture 2 when the gauge set is removed?

EDIT: I just looked closer at picture 2. The gauge line with the valve appears to be connected to the nylon line that goes to the wur. If that's correct, then when the gauge set is removed, that nylon line is attached to the port of the distributor where the gauge set is now connected. Correct? If so, we are on the same page. As stated before, the connections shown in picture 2 are what I use, and will produce accurate pressure readings. I've never connected through a banjo fitting.

[boyt911sc]

Glen,

Could you post some pictures showing the WUR and its fuel line connections? Your data is very well organized but I seemed not to follow your description of the WUR's connections. BTW, my reference booklet shows 0-438-140-001 for '73.5 and -008 for '74. Thanks.

Tony

[Glen Pettigrew]

L.J;

Thanks much for you're continued interest in my problem.

In you last paragraph beginning with, EDIT:
you got it correct. I have two choices for measureing 'System Pressure';
1. connect guage through the banjo fitting that goes to 'Throttle position
regulator'. This gives me a 'System Pressure' of about 3.3 BAR with throttle
in the idle position.
2. Remove and leave hanging the Banjo connector that goes to the
'Throttle position regulator, and connect guage to the fuel distributor
port all by itself. This gives me about 5.8 BAR.
Book says it should be between 4.5-5.2 BAR.
So, measuring it the first way is too low and measuring it
the second way it is too high.

Which is the correct way of measuring it?

Tony;
Thanks for you're interest.

The PET parts catalog shows the same WUR part number on 73 & 74 CIS
systems. Please see attached pictures which are of mine.





Thanks much...
Glen Pettigrew

[kodioneill]

That WUR if from a 1973.5 CIS system it's non adjustable and may possibly be the incorrect one. You have to check system pressure as well as running pressure. I would check for contamination in the fuel tank buy pulling the gauge sending unit and looking inside the tank with a flashlight.

[ossiblue]

Glen,

Possibly this accounts for my procedure versus yours. First, you wur is NLA and has been superceded by 0-438-140-129 which is rebuildable and adjustable. Second, because of the set up of your fuel inlet, you attach the gauge set to the fuel distributor port. When I test my system, I detach the fuel line from the distributor to the wur at the connection of the wur. That will leave all connections intact on the fuel distributor--meaning the line to the throttle positioner is still connected. Possibly, that accounts for the slightly high reading on your pressures--there is no "bleed off" to the throttle positioner because it is disconnected.

If you have the adapters, you might try disconnecting the line from the fuel distributor to the wur, at the wur, and connect it to the inlet of your gauge set or, leave the throttle positioner connection intact and connect the gauge set as you've done.

Edit: Just checked my reference book. It states the gauge set inlet connects to the fuel distributor and the valved line connects to "the control pressure regulator and throttle valve." To me, since the throttle valve connection is a banjo fitting on the distributor, the only way to "connect" it to the valved side of the gauge set is to have it in line with the fuel circuit as it returns from the wur--in other words, keep the banjo fitting to the throttle valve connected at the fuel distributor and connect the gauge set through the banjo fitting so the throttle valve remains in the completed fuel circuit.

[Glen Pettigrew]

kodioneill;

I appreaciate your suggestions.
Since I was able to get approx 1.2 Liters of fuel
out of the fuel filter outlet, can't image that I
would have any obstructions in fuel tank.
Please explain what you mean by 'running pressure'.

Thanks...
Glen Pettigrew


L.J;

Yes, I understand that my WUR cannot readily be taken apart.
Although I could probably still do the Drill/Tap routine
from the outside to make it adjustable.
I do have a few other WURs that can be taken apart.
Although they all have the Vacuum connection on them.
I am unable to disconnect the fuel inlet line at the
WUR since it is pressed on and would be distructive
to remove it with heat/cutting it.
From your description, It would appear that setup #1
is the correct way to measure 'System Pressure'
That being so, My measurement System Pressure is too low.
Although my Cold & Warm pressure is too High.

Should I be concerned with/try to fix 'System Pressure'
too low problem?

Or, should I ignore 'System Pressure' and concentrate
on my Cold & Warm pressure being too high?

I can either try adjusting or replacing my WUR to get
Cold/Warm Pressure correct.

I have already removed the shims in the Fuel Distributor
Pressure Relief Valve, That is what brought down
the 'System Pressure' measure in Setup #2 from
6.5 BAR/95 PSI to 5.8 BAR/85 PSI.
-------------------------------------------------------
Setup #1:

WUR----V---T-----TPR-FD
|
|
G

Measured Pressure with Valve Closed: (System Pressure?)
3.3 BAR/47 PSI
--------------------------------------------------------
Setup #2:

WUR-TPR-V--T---------FD
|
|
G

Measured Pressure with Valve Closed: (System Pressure?)
5.8 BAR/85 PSI

Per Book, System Pressure s/b 4.5 - 5.2 BAR

WUR = Warm-up-Regulator/Control Pressure Regulator
TPR = Throttle Position Regulator
V = Valve on Guage set.
T = T part of Guage set.
FD = Fuel Distributor
G = Guage

Thanks much...
Glen Pettigrew

[Glen Pettigrew]

Please excuse the text diagrams for setups #1 & #2.
The vertical lines and 'G' symbol are supposed to come from the
'T' intersection of the Guage setup. Spacing got messed up
after posting the reply.

Thanks.
Glen Pettigrew

[boyt911sc]

Glen,

Could you post a picture where the fuel return line from WUR goes to? I'm having a problem following the 'banjo' fitting you mentioned earlier. I would like to see where the return fuel line from WUR is connected to and after that. Thanks.

Tony

[ossiblue]

Tony,

The banjo fitting appears to be unique to the 73/74 system. There are 7 fuel lines on the top of the distributor (six connected to individual ports for the cylinders with banjo fittings, and the seventh, for the throttle valve, connected in line with the port to the wur). I'm not familiar with that set up as 75 and on do not have that seventh line. If you look closely at the second picture, you can see the line attached--just behind the connection for the gauge--and running off to the upper left. He also circled it in red in picture 1.

Glen,

All of my previous posts, above, assume the "throttle valve" mentioned in my spec book is the same as "throttle position regulator" that you mention. Maybe I should step back a bit as I've not worked with the "extra line" on a FD. From my source book, however, it looks like your set up #2 is the one to use as the "throttle valve" is connected to the valved side of the gauge set up. At this point, you may wish to follow Tony's suggestion and clarify the return connection from the wur.

[Glen Pettigrew]

retrogarage;

Looks like you nailed it after all! Thanks so much for you advise.

I disconnected the fuel return line at the hard line in the front left of engine area.
Put the fuel line in a bottle and checked the System Pressure at the
fuel distributor and it was down in the 3 bar range. Attached air hose
to the hard line and still heard bubbles in tank. But, this time I removed
the Fuel sender on top of the tank.I left the air hose (about 80 PSI) on
there for a few minutes and the bubbles got louder and louder. Hooked
the fuel return line back up and was able to adjust the System Pressure
to exactly 4.8 BAR with shims. After that, I was able to adjust the
WUR (P/N 0438.140.001 has a large screw on the bottom that adjusts
tension on coil spring) to the exact specs in book. Car now runs great
with no hesitation/ bucking at the 2000 -3000 RPM range.

kodioneill;
Thanks for your assistance in working on my problem.
As it turns out the WUR that I have is adjustable by design,
no modifications necessary.
I did inspect the tank while I had the sender removed and it looks
spotless, no debri, rust or anything else in it.

L.J.;
Thanks for your assistance in working on my problem.
As you stated, the System Pressure is measured with the Throttle
Position regulator and the WUR disconnected from the Fuel Distributor.
After clearing the blockage in the ruturn line the system pressure
was easily adjustable. And, the Control pressure is set
with the Throttle Position regulator and WUR connected.
As stated above, my WUR is designed to be adjusted via large
screw on bottom.

Tony;
Thanks for your assistance in working on my problem.
For your reference, The fuel return line from the Fuel distributor
goes to a connector (like a 'double 'T') that has the return line
from the Throttle Position regulator, the return line from the
WUR and continues to the hard line in the front left of the
engine area.

Thanks again to all that contributed to the solution of my problem.
I learned alot from you.

Glen Pettigrew

[retrogarage]

Glad I could help. Pretty cheap fix then? The inlet and outlet at bottom of tank are very low on tank and very easy to clog with junk after car has sat for awhile.

[ossiblue]

Good news Glen. Always a pleasure to hear the results of efforts made on the forum. Enjoy the fruits of your labor, your perseverance, your willingness to ask questions, and the collective knowledge of the Pelican World.

[kodioneill]

You're one thorough dude and a class act!

[prebordao]

Originally Posted by Glen Pettigrew

After that, I was able to adjust the
WUR (P/N 0438.140.001 has a large screw on the bottom that adjusts
tension on coil spring) to the exact specs in book. Car now runs great
with no hesitation/ bucking at the 2000 -3000 RPM range.

Glen Pettigrew

I've always read that early type WUR's (001's like this) were not adjustable.
So they are after all ? Can anyone chime in ?

[ossiblue]

Originally Posted by prebordao

I've always read that early type WUR's (001's like this) were not adjustable.
So they are after all ? Can anyone chime in ?

I think that they are not rebuildable, but are adjustable as Glen has shown.