CIS no start issue -'77 911S
 

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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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.

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.

"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

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

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.


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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

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.

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.

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.

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.

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?

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?

Air leak detection for CIS........
 

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.

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. http://forums.pelicanparts.com/6628676-post12.html

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

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:

http://forums.pelicanparts.com/uploa...1332380571.jpg

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

Wow, looks like whiskey! From the picture I think you have found a problem. Looks like you may have a fun solution in the lower right corner...Unless that's to protect the still! :)

Check valve and/or accumulator from everything I've read. Cis primer explains the functions well.

STILL no luck!

I drained about 18 gallons of caramel colored fuel out of the car last night (see the photo I posted earlier).

The car still refuses to start.

I pulled all the plugs and cleaned them, thinking that I may have fouled them with all the previous attempts. No change.

I'm pretty much stumped now.

Where on earth do I go from here?

Any advice - and I mean ANY - would be appreciated. Ask me questions, whatever. I am COMPLETELY stumped now.

- Damion

Have you attempted to start the engine using starting fluid yet? This may help isolate a fuel from an ignition issue.
regards,
al

I have tried starting fluid. No go with the starting fluid, either.

I guess it could be an ignition issue, but I don't know what else to test with regard to the ignition. I have brand new Bosch copper plugs in the car now. I have spark at the coil and at each individual plug. I pulled the distributor out and did the test for the Petronix ignitor (using a multimeter).

Is there something I am missing, re: testing the ignition?

I don't know if I would call this advice or something else but here goes:

Here is what I did to get my car to start on Sunday (4 days ago)when I had a huge vacuum leak due to my own error after R&R of the entire CIS system.
Taught me a lesson I'll never forget and I will never repeat the same mistake that had me going down this road.
(Not for the faint at heart)
Write down everything you do, so you can undo it.
1. Turn your richness screw with a 3mm wrench 1 complete turn clockwise, try to start, if it sounds like it wants to catch open the airscrew one or more entire turns, try to start again.
If it doesn't work, repeat and richen the mix again.
I had to richen my mixture 4 complete 360 degree turns and open the airscrew about 8 turns to get my car to start and run with the hose off the AAR as I mentioned in an earlier post in this thread.
Found the reason and fixed it, undid all the adjustments I made and she runs well again.
Proof positive that you can mask a vacuum leak by increasing the richness and adjusting the air mixture screw.

My theory for you to try this is to prove it can run and that you may have a CIS vacuum problem that you haven't found yet.

I had my airbox off because of a suspected leak (besides the one I put in it on re-assembly). I completely disassembled the airbox and plugged all holes and vacuum tested it.
I know I don't have a vacuum leak anywhere. (new boots and CIS component seals too!)

You decide if you want to try it. I can offer suggestions for pulling the CIS with the engine in car if you need them.

I'm starting to want to see that car running almost as much as you are!:D

Up until last night I had been more or less ignoring the residual pressure issue because my fuel pump runs when the ignition is turned on.

However, because I'm running out of options, I checked the fuel accumulator last night. The bottom fitting holds vacuum without any leaking. I think this means that the accumulator checks out.

So I next checked residual pressure with the valve on my pressure tester closed. It holds right at the system pressure of 70 psi.

I did some more reading and then pulled out the "primary pressure valve" in the fuel distributor. It was immaculately clean. More importantly, it is of the "single spring" type.

At this point I realized I'm chasing my tail. The WUR outlet goes directly back to the fuel tank. There are no check valves or regulators AFTER the WUR. The only possible source for residual pressure loss would be the WUR itself.

The fuel pump check valve, the fuel accumulator, and the PPV are all upstream of the WUR.

Sure enough - the 911 workshop manual confirms this - if the residual pressure does not drop when the valve is closed (position 3 in the manual) the problem can be in the [warm up regulator] or control pressure regulator. Since my car does not have a control pressure regulator, that leaves the WUR.

The manual says the test for the WUR is to disconnect the WUR outlet (with the fuel pump shut off). If it leaks with a residual pressure between 1.5 and 2.4 bar, the WUR has failed. Of course, if the residual pressure is zero, that would suggest the same thing.

I also see that around 1978 Porsche added a check valve to the PPV and routed the WUR outlet to that check valve. Apparently they found that the WUR doesn't do a great job when it is acting as a check valve. This actually makes sense, since prior to '76 the residual pressure shouldn't have been much of an issue, but once they added the microswitch for the fuel pump, the retained pressure became a more significant problem.

Unfortunately, none of this solves my problem. However, it is one more thing to cross off the list.

Of course, it does raise a few other questions - for example - why on earth was my control pressure zero before I cleaned out the WUR?

Also - why is the WUR not retaining any residual pressure?

I have a theory on this - I have my cold control pressure set at 11 psi. If I'm understanding the system correctly, this would mean that the pressure valve is only exerting a small amount of pressure on the fuel flow. Put another way, the WUR is permitting the vast majority of fuel to flow through the WUR and back to the tank. A pressure drop is expected after the pump is shut off, so maybe with a warm WUR I would have some residual pressure.

Anyway, sorry for the long post. I'm still looking for advice, hints, or tips.

One question - is there a "baseline" setting for the mixture screw? My car obviously had its fuel injection messed with in a past life, and I have no idea where I'm working from with some of these settings.

WUR tests.......
 

You are doing it all wrong!!!!! Please send the WUR to me and I'll have it tested ASAP. Right now, I have four (4) WUR's from Pelican members that I'm testing this weekend. Include the return address with stamps. This is not FREE. I'm charging you $0.10 for the work. Take note of the stamped numbers on the WUR. The casting #980 or 916, Germany/France plus the three (3) digits. Do not confuse the marking with 0-438-140-xxx. PM me.

Tony

What am I doing wrong?

Do you mean I'm testing the fuel pressure incorrectly?

I need you to be a bit more specific.

Thanks,
Damion

A few comments.

First, take Tony up on his WUR testing or, at least, PM him and get specific with your questions. He has done lots of hands-on work with CIS and knows what he is doing.

Second, the WUR is the control pressure regulator--it goes by both names, the most common on this board is WUR.

Third, you apparently know how to do the pressure tests correctly. Currently, you have a residual pressure of "0", correct? When you cleaned out the WUR, did you replace the 0-ring in the diaphragm cover? (Sorry, I did not go back and re-read the entire thread.) Did you inspect the two diaphragms for any bends?

Fourth, 11psi is very low, below 1 bar. Most specs on residual pressure are ~1 bar so from the outset you are low. However, a functioning wur should still hold that pressure.

Finally, you might try the following and report back: You say your fuel pump runs with the ignition on (even though it shouldn't). When you try to start the car and it fails to fire, immediately shut it down and go pull the plugs--what do you see and smell? Are they gas soaked or dry or something in between? Remember, every time you crank the engine, raw gas is shooting into all the intakes at once. If you are not burning off that gas, it is accumulating in the cylinders and seeping into the crankcase and into the exhaust. You put in new plugs, so you should be able to see signs of ignition, if it's present.

The fact that you can't get ignition using ether makes me suspect fuel delivery may not be the major factor here.

Do the basic test first........
 

Damion,

Since you asked, I reluctantly will tell you to:
1). Establish that ignition sparks is produced during cranking!!!!! And reproducible.
2). Forget the rest of the CIS troubleshooting for they would be useless until you confirm this requirement (ignition sparks).
3). Run the FP and measure the control, system and residual pressures. Record the cold control fuel pressures from start (cold) till it stabilizes and may take 4 or 5 mins. Continue the observation until the cold control fuel pressures becomes the WCP. This is a critical test because these data would be your baseline data for your WUR.
4). Leave the air mixture screw alone at this point. This is used for fine tuning with a gas analyzer unless someone has disassembled the air metering unit before and you are starting from a rebuild.
5). How did you confirm that you don't have any vacuum/air leak? Not being able to see one does not mean you don't have any!!!! Test and confirm.

Lastly, your FP should NOT be running with the ignition switch @ ON position. There is something very wrong with your set-up (electrical). Your understanding of a WUR is flawed. It is not a check valve unit but rather a pressure regulator device. We could debate and discuss about the literature but let's put it aside and focus on the culprit/s. Keep us posted.

Tony

1. I'm going to PM Tony and see what he suggests.

2. I was referring to the workshop manual testing procedure - earlier CIS cars had two control pressure regulators - the WUR and another on the throttle.

3. I did not replace the o-ring. No problems that I could see with the diaphragms.

4. I agree that the pressure is low. I found a chart that showed a very low cold pressure for the '77 911, and I thought I would try that pressure. No change.

5. What are the "signs of ignition" that I should be looking for?

Honestly, I agree that it seems like more of an ignition issue than a fuel issue, but I simply do not know what else to test with the ignition. Spark at all six plugs and I checked the gaps (again). Tested the distributor (and installed it 180 degrees out of timing at one point). Nice bright blue spark at coil. Is there something else I should look for?

You drove the car to the shop.......
 

Damion,

If your ignition timing was 180° off you'll never be able to drive your car to the shop or start the engine!!!!!! So leave the air mixture setting and distributor out of your troubleshooting. They are good.

I'm putting my money on two things:
1. A significant air /vacuum leak some where that is affecting the combustion of the fuel-air mixture.
2. Ignition problem.

I'm re-reading your posts and noted the above.

Tony

Cross country drive in May......
 

Damion,

The '87 Carrera that I bought for my son who lives in Carmel, CA will be driven cross country very soon. Need to drive the car more and get confident that it could take the long drive (3600 miles) to CA. I would not hesitate if I am taking my '78 SC but this '87 Carrera is new to me. What's your zip code?

Tony

Tony,

Thanks for the info. Here are my replies:

1) Spark is being produced during cranking. I checked it at all six plugs (with the assistance of the wife).

2) If there is some other ignition test for me to try, let me know. I'm all for it.

3) I have not done a check from cold to warm on the WUR. I did test the resistance a few times. I'll do this next.

4) Ok.

5) I pressurized the intake using the vacuum line that runs to the brake booster (I think that is where it goes - it connects below the throttle body and is a large sized hose). I sprayed everything repeatedly with a soap and water solution and could not find any leaks (other than around the pop-off valve and through the metering plate). Still not certain, I removed the intake boot and plugged the large hose that attaches in the back of the boot. I also capped the throttle body. Still couldn't find any leaks. So I then went and duct-taped my shop vac to the vacuum line and - don't laugh too hard - blew cigar smoke all over the engine. I checked to see if this would work by lifting the pop off valve slightly and it sucked in smoke readily. I'm not saying that there are no leaks, but I don't think there is a really large leak anywhere. But maybe there is... ?

6) I know the fuel pump should not run with the ignition. The car has been "rigged" like that since I bought it 12 years ago. I never bothered to figure out how they rigged it up that way, but the microswitch was completely removed.

The distributor was off 180 degrees at one point after I pulled it out to test the ignitor. It was fairly easy to determine - huge backfire.

15845.

Check the back (towards front of the car) of the pop-off valve cement joint using a dental mirror. It's impossible to see without the mirror.

Like to see picture of your test......
 

Damion,

The pressure test would only work if you successfully inject positive air pressure into the system. This means the air metering unit should be excluded and plug all the hoses after removing the CIS rubber boot (throttle body to air metering unit). Install a latex glove on the throttle body and secure it.

Since you are doing the test and we have no idea what's going on except what you tell us, feedback is critical. Could you demonstrate (picture) that you are able to maintain a positive air pressure with 2 psi air supply? The latex glove should be inflated and maintain that condition during the test. Keep us posted.

Tony

Since you have determined that you are getting both fuel and spark... and you are not getting it to start, using starting fluid....I am going to suggest that you have an ignition timing issue. You say that you are getting spark, but have you determined, using a timing light, that your timing is correct.

regards,
Al

Residual fuel pressure test........
 

Damion,

I re-read your posts several times to determine what's been done in your troubleshooting saga. In your post #26 (3rd paragraph), you mentioned how you checked the residual fuel pressure. That's not the way to check the residual fuel pressure for CIS!!!!! First you have to measure and determine what's your control fuel pressure and start from there. You are not doing the right procedure.

The test you did could be used to check the FA, FD primary relieve valve, and FP check valve but not the residual pressure for CIS start-up. You need to measure the residual fuel pressure with the valve OPEN not closed!!!!! Keep us posted.

Tony