CIS no start issue -'77 911S

[djb25]

Hi everyone,

I'm having an issue with my '77 911S.

Here's a rundown of the situation:

Car was only occasionally run in the last year. It sat from May through November.

November - Car was running. Started a little hard, but nothing severe. I drove it a short distance (appx 2 miles) to my body man's shop for a full repaint. When I got to his shop, the idle was really high (2000 rpm). I ignored that at the time.
Fast forward to two weeks ago. Body man says the car won't start (first he's tried to start the car).

Since then I have:

1) Checked spark at coil,
2) Tested pertronix igniter (ok). Had to statically time the distributor after this.
3) Changed distributor cap

I located my missing spark plug wrench at this point.

4) Pulled and cleaned plugs.
5) Pulled and checked auxiliary air regulator

I installed pressure gauge at this point

6) System pressure = 70 psi, cold pressure = 0 psi! Pressure bleeds off in about 30 seconds or less.
7) Pulled WUR and completely disassembled it. Cleaned it out with carb cleaner. Reinstalled. Cold pressure is now around 20 psi. Residual pressure leaves quickly as before.
8) Tested electrical connection to cold start valve. Has power while cranking. Also - can smell fuel after trying to start.

At this point - car sounds like it is trying to start. I get little putters while cranking. Previously the car would crank and crank without any response.

Where do I go from here? Pull the injectors?

Any advice would be greatly appreciated.



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[ossiblue]

My thoughts from your post.

First, the high rpm's when you last ran the car could indicate an air leak that will complicate any starting procedures.

Second, your cold pressure is dependent on ambient temps so it's hard to know if it is in spec. It could be too low which will make cold starting difficult.

Third, your loss of residual pressure needs to be addressed since the fuel pump only runs when the starter is engaged and you may not be getting adequate pressure to fire the engine.

If it were me, here's what I would do, in this order:

1. Check and set cold pressure to spec.

2. Turn on the ignition, lift the plunger in the intake, and bleed the fuel system until the injectors squeal/vibrate.

3. Immediately, try to start the car.

Report back with your results. If the engine starts and runs, you can then investigate other possibilities as to how to repair your loss of residual pressure and idle conditions.

[Bob Kontak]

As a side note, ossiblue or boyt911SC pointed out a few months ago that if the WUR is plugged or the return line to the tank is plugged the cold control pressure will be equal to system pressure given the system pressure cannot be reduced through the control pressure regulating function. Seems odd that you would have zero pressure and then 20 psi after a clean out.

+1 on ossiblue's recommendation.

[Lorenfb]

"cold control pressure will be equal to system pressure given the system pressure cannot be reduced through the control pressure regulating function."

- Bob Kontak -

Actually, the system pressure is not affected by the control pressure, i.e. the control
pressure affects the quantity of fuel delivered thru the injectors. The greater the
control pressure, the less will be the fuel delivered.

To eliminate fuel as an issue, try spraying carb cleaner into the intake and see if
the engine will continue to run. If so, then make sure the cold control pressure
is about 20-30 psi and the warm is 50-60 psi with the system pressure about 70 psi.
Make sure the injectors are not sticking or not fully opening.

Check here for more info: Diagnostic

[djb25]

A few additional notes:

The fuel pump in my car runs whenever the ignition is on. It's been like that since I bought it 12 years ago. I know it isn't supposed to work that way, but I never got around to tracing the reason for it.

I didn't just clean the WUR - I disassembled it completely and cleaned the entire thing out. As soon as I reinstalled it the cold pressure showed 20psi. It definitely showed zero before. I think the diaphragm in the WUR was sticking open. System pressure remains around 70 psi.

According to http://jimsbasementworkshop.com/CIS/Testing/wur_specs.html the cold pressure for my car should be either 1.4 bar (20 psi) or 0.8 bar (11.5 psi), depending on the WUR. I'm going to double-check the part number, but I believe my WUR is .033. It was about 55 degrees in my garage at the time I checked the pressure. I've checked it two or three times since then, it's been consistently 20psi.

I'm going to look into the air leak suggestion next.

I did pull one injector this morning and it patterned well. I didn't have the time to pull any other injectors.

What about the AAV? It's not exactly easy to get to, but could that be causing a problem?

- Damion

[djb25]

Next question - does anyone know of a guideline for removing the CIS system from the car? I think I'm going to just pull the system and replace a bunch of seals. Most of the intake runner to air box boots are cracked. I'm not sure if they're leaking or not, but they look poor.


Sent from my iPad using Tapatalk HD

[al lkosmal]

1st, I would follow the suggestion of using some starting fluid. If your engine start using it, you know you have a fuel delivery issue vs. an ignition issue.
2nd...........a vacuum leak can cause this. do you have a pop-off valve? did you ...or your body man notice a backfire, while trying to start your 911? If so......check that the pop-off valve is firmly seated, closed and still bonded properly.
3rd...check that there are no cracks in your intake box.

regards,
al

[T77911S]

Originally Posted by Lorenfb

"cold control pressure will be equal to system pressure given the system pressure cannot be reduced through the control pressure regulating function."

- Bob Kontak -

Actually, the system pressure is not affected by the control pressure, i.e. the control
pressure affects the quantity of fuel delivered thru the injectors. The greater the
control pressure, the less will be the fuel delivered.

To eliminate fuel as an issue, try spraying carb cleaner into the intake and see if
the engine will continue to run. If so, then make sure the cold control pressure
is about 20-30 psi and the warm is 50-60 psi with the system pressure about 70 psi.
Make sure the injectors are not sticking or not fully opening.

Check here for more info: Diagnostic

it actually is...in a way
the 70 psi system pressure is sent to the WUR and reduced, and is then renamed control pressure. if the WUR inlet screen is clogged, control pressure can be as hi as system pressure, which is what he was refering to above when he said system pressure cannot be reduced.


OP:
i dont think you need any starting fluid.
do as ossi has said, but also note the feel of the sensor plate when you lift it. with the FP running, you should feel resistance on the plate. if there is ANY play before you feel resistance, the plunger is stuck.
you could even pull all the injectors and place them in jars to verify one, they dont spray when the FP if on and the sensor plate is at rest, and second, they all spray when the sensor plate is lifted.
your CCP sounds about right, although i am with the others as to why you had 0psi and now 20psi. not the norm.
replace the plugs. they are likely fouled after all this.
next check the cold start system.
the AAV and the AAR will not keep the car from starting. they just add air, like putting your foot on the gas, while starting, and holding it there after it is started.




this is all based on you have spark.

[djb25]

Originally Posted by T77911S

OP:
i dont think you need any starting fluid.
do as ossi has said, but also note the feel of the sensor plate when you lift it. with the FP running, you should feel resistance on the plate. if there is ANY play before you feel resistance, the plunger is stuck.
you could even pull all the injectors and place them in jars to verify one, they dont spray when the FP if on and the sensor plate is at rest, and second, they all spray when the sensor plate is lifted.
your CCP sounds about right, although i am with the others as to why you had 0psi and now 20psi. not the norm.
replace the plugs. they are likely fouled after all this.
next check the cold start system.
the AAV and the AAR will not keep the car from starting. they just add air, like putting your foot on the gas, while starting, and holding it there after it is started.

this is all based on you have spark.

Ok, I checked the sensor plate and I feel resistance. No free play.

I don't know what to tell you guys about the cold pressure. I looked into it before opening up the WUR and I found a thread about it. Basically the WUR was not regulating at all, all fuel was flowing through?

I also already checked the cold start valve. Checked for voltage and the related.

Maybe I should swap out the plugs and see if that helps...

[ossiblue]

Originally Posted by djb25

Ok, I checked the sensor plate and I feel resistance. No free play.

I don't know what to tell you guys about the cold pressure. I looked into it before opening up the WUR and I found a thread about it. Basically the WUR was not regulating at all, all fuel was flowing through?

I also already checked the cold start valve. Checked for voltage and the related.

Maybe I should swap out the plugs and see if that helps...

One thing I noticed as I re-read your original post is that you checked the spark at the coil but, apparently, not at the plugs. Probably insignificant but since your fuel delivery issues seem to be okay, I think a change out of the plugs is in order as you do get a "sputter" but not full ignition.

Don't forget you still have a residual pressure issue and a likely air leak problem as well. After changing the plugs, be sure the system is pressurized and give it a try.

[T77911S]

replace the plugs as i said. they can foul
then check spark at the plug.
go ahead and lift the sensor plate with the key on and then give it a start. ( a quick check of the CSV system).
there may be voltage at the CSV, but it could still be bad. if it fires up with the above, dive back into it, if not, back up and punt.

if the CSV circuit is working, usually you will get a a quick fire and it will run for about a second or 2 then shut off and not fire again.
if it does not fire at all, look to the CSV or ignition.
also, if you have had the dist out, recheck it. make sure you are not 180 out (usually you get loud backfires) or off by several teeth. you may have fixed one problem and created another.

one other thing you can do is have someone else start it while you lift the sensor plate, or pull it down. ( if for some reason the mixture is way off, this is a crude, non permanent way to compensate). lifting up makes it run richer, down equals leaner.

this is a more or less if all else fails order.

dont forget air leaks.
do you, well your car, have a pop off valve? check to make sure it is seated properly. they can open and not close all the way.

[djb25]

Hi everyone.

I haven't had a chance to look into the car any further today.

I did check spark at a few of the plugs and it seemed strong, but I didn't check every single plug.

A malfunctioning CSV would make a lot sense, perhaps it isn't firing.

Hopefully I'll get a chance to check into things soon.

[djb25]

Latest update.

Pulled the csv and it is functional. Also pulled and cleaned out the aav (already pulled, cleaned, and tested the aar).

Have new plugs coming tomorrow.

Starting to run out of ideas now. Possibly a major air leak?

Any other theories?

[djb25]

Ok. Swapped in the new plugs. Gapped them to .7mm. No change. Occasionally got a slight sputter, but nothing I haven't heard before. At no point did the motor actually fire.

I think I'm down to a major air leak. I tried to locate a leak without pulling the intake, but I'm not finding anything.

I'm probably going to pull the intake next, unless there is some better way to check for leaks without pulling the intake? Where does everyone inject air when they test the intake?

Is my cold pressure ok at 20 psi at 50-60 degrees ambient temperature? It appears that it is correct...

Any other suggestions for me?

[boyt911sc]

Originally Posted by djb25

Ok. Swapped in the new plugs. Gapped them to .7mm. No change. Occasionally got a slight sputter, but nothing I haven't heard before. At no point did the motor actually fire.

I think I'm down to a major air leak. I tried to locate a leak without pulling the intake, but I'm not finding anything.

I'm probably going to pull the intake next, unless there is some better way to check for leaks without pulling the intake? Where does everyone inject air when they test the intake?

Is my cold pressure ok at 20 psi at 50-60 degrees ambient temperature? It appears that it is correct...

Any other suggestions for me?

djb,

A very simple and easy way to locate air/vacuum leak in a CIS engine had been discussed in several of my previous posts about CIS troubleshooting. A continuous supply of pressurized gas (air, nitrogen, argon, etc.) to the engine (system) at around 2+ psi is sufficient to reveal the presence of air leak/s if any. I've been following this post since the very first day and keeping my distance until now.

Hook up an inductive timing light and see if you are getting signal during cranking. Keep us posted.

Tony

[djb25]

Originally Posted by boyt911sc

djb,

A very simple and easy way to locate air/vacuum leak in a CIS engine had been discussed in several of my previous posts about CIS troubleshooting. A continuous supply of pressurized gas (air, nitrogen, argon, etc.) to the engine (system) at around 2+ psi is sufficient to reveal the presence of air leak/s if any. I've been following this post since the very first day and keeping my distance until now.

Hook up an inductive timing light and see if you are getting signal during cranking. Keep us posted.

Tony

Okay, I went crazy with air leak testing and found nothing. I even went as far as to remove the intake boot and cap off the throttle body (and aav). I could not locate any leaks. I did find that the pop-off valve leaked a little bit around the rubber o-ring when under pressure, but a slight amount of pressure eliminated the leak. If I pulled up on the valve slightly, I got gigantic bubbles immediately, so my soapy water solution was apparently functional.

Next I checked spark at each of the plugs. I found a nice, healthy blue spark at each plug.

Next I thought that perhaps I had the timing off by 180 degrees, so I reset the static timing. That change resulted in a very, very loud backfire (through the exhaust, not the intake). I'm guessing that the timing was correct.

Next I tapped the WUR pin down and reduced my cold control pressure to about 11 psi, which is another setting that I found for the '77 911S. Again - no change.

Next I pulled three injectors (cylinders 1, 2, and 4 - the easiest to reach). I tested each spray pattern. All three patterned well and none of them leaked. I can pull the other three, or all six and test their flow rate, but could one or two bad injectors cause this no start problem?

I'm about to lose my mind here.

One thing I haven't mentioned - my Optima battery is about shot. It won't hold a charge so I've been jumping the car off of my truck. Could the battery be causing a problem somehow?

The last possible thing I can think of = bad fuel. The fuel in the tank is fairly old... I can't say how old, but it's definitely from sometime last year. Should I drain the tank and replace it with fresh fuel? Does the ethanol blend cause more longevity issues?

I never had starting issues with this car in the past. I used to pull it out of winter storage and it would start almost immediately.

[timmy2]

Get a new battery.
Ethanol is horrible for storage. The alcohol absorbs water.
Pull your supply line at your accumulator and hook up a hose to a container, run your fuel pump with the jumper method to empty your tank, and get rid of it in your lawnmower after adding some octane boost.
Add new gas, run it through the system until you see nice clean flow out of all 6 injectors.
During your testing have you checked the vacuum booster line to see if it holds vacuum? Could be the massive leak you are looking for.
I left a hose off of my AAR (Big yellow/gold disc thing) in the back of the CIS that I couldn't see. The rubber y-pipe back there has been known to crack, have you put a mirror back there to inspect the rear hoses and connections?
Like this post shows. 1976 911S – from garage find to on the road

[djb25]

Originally Posted by timmy2

Get a new battery.
Ethanol is horrible for storage. The alcohol absorbs water.
Pull your supply line at your accumulator and hook up a hose to a container, run your fuel pump with the jumper method to empty your tank, and get rid of it in your lawnmower after adding some octane boost.
Add new gas, run it through the system until you see nice clean flow out of all 6 injectors.
During your testing have you checked the vacuum booster line to see if it holds vacuum? Could be the massive leak you are looking for.
I left a hose off of my AAR (Big yellow/gold disc thing) in the back of the CIS that I couldn't see. The rubber y-pipe back there has been known to crack, have you put a mirror back there to inspect the rear hoses and connections?
Like this post shows. 1976 911S – from garage find to on the road

Thanks, but I'm pretty sure I've checked all of the vacuum connections. I did a "partial" engine drop and checked everything at the rear of the engine, including the AAV. All the connections looked good. When I pressure tested the intake I put a plug in the end of the hose you're referring to and it held pressure.

I'm off to drain the tank now and see if I can get anywhere with some fresh fuel.

- Damion

[timmy2]

Originally Posted by djb25

Next question - does anyone know of a guideline for removing the CIS system from the car? I think I'm going to just pull the system and replace a bunch of seals. Most of the intake runner to air box boots are cracked. I'm not sure if they're leaking or not, but they look poor.

Re-reading all of your posts.

Did you replace these? They are almost impossible to test with bubbles on the passenger side under the box with engine in the car. Could be your huge air leak.

Have you fixed the residual fuel pressure immediately going to zero by replacing the accumulator?

I pulled and re-installed my CIS system on Sunday with engine in car. Changed my airbox.

[djb25]

Originally Posted by timmy2

Re-reading all of your posts.

Did you replace these? They are almost impossible to test with bubbles on the passenger side under the box with engine in the car. Could be your huge air leak.

Have you fixed the residual fuel pressure immediately going to zero by replacing the accumulator?

I pulled and re-installed my CIS system on Sunday with engine in car. Changed my airbox.

I didn't replace the boots, but if they are leaking, it isn't a major leak. I actually went higher than 2 psi when pressurizing the intake and I did not find any "major" leaks (I actually didn't find any leaks, but I'm acknowledging that it is hard to completely test with the engine in the car).

I thought the residual fuel pressure issue was due to the fuel pump check valve, not the accumulator?

On a related note:



Take a guess - fuel from my Porsche or fuel from my backyard still?