Ehhh, drive it some more and observe and think about its behavior. Eventually you'll figure it out.

Ok, I've been driving it a bunch. It still is driving flawlessly - except the starting. I am trying to think of what might be part of the starting that is not working right. My English sports car when the starter is cranking, it gets a full 12V - but during running operation, it has a resistor that drops the voltage to the coil. Is there any similar mechanism with the 911 that might not be working here?

Also, I note that after I try to start it a number of times, it starts smelling like gas. I'm assuming this is because the cold start valve is pushing out gas, and it's not starting. I've tried starting with and without the cold start valve and I can't find one process that works better than the other to get it to start.

It starts best when cold. But needs a number of cranks to start when hot and warm (like a couple/few hours warm).

As indicated above, new accumulator. New return valve on end of fuel pump. Injectors spray nicely, and don't really leak when off. One was a tiny bit more than the others, but that has gone away since I cleaned them.

CIS Troubleshooting……….
 

Jay,

If I were in your shoes, I will focus my investigation why you are not igniting the fuel on the first crank. There are many factors that could affect this behavior (multiple attempts) like fuel delivery, poor ignition, residual pressure, etc. Your car should start and run at the first attempt (ideal) but life is not fair. If it is not starting all the time on the first try, there is a flaw in the system. Identifying this culprit requires a systematic test procedure to identify the culprit. And replicate the test procedure if you discover a likely candidate. Test and confirm before declaring victory.

Tony

For "ha-ha's", try a can of LiquiMoly Jectron to try to remove and remaining impurities in the fuel system can't hurt.

I just went through the entire thread to make sure I've tried everything everyone suggested, and I have done them all.

But I circled back to the leaking after shut off. Just how much leakage is ok? The car tests fine on the residual pressure test. So I have to assume whatever leakage I have is fine. But, I'm definitely getting a small amount. Any ideas of what is too much? - Just pulled them and put in jars. Most are pretty dry. One has maybe 5 cc of gas in the jar after a couple hours. I have a replacement on the way. Different is different. So at least I'll address that.

I do note that once it does start, it starts immediately smooth. It isn't burgling around as the injector fills. So that's why I would not think this one injector's leak is material. But maybe I'm wrong.

The one thing that I've not touched has been the FD. I understand leakage from there can cause hard start problems. And that leakage out the injectors is really the FD, not the injectors. But with the other injector on the way, we'll see if that changes anything.

Here are things already covered:
New accumulator
New one way valve on fuel pump
New fuel filter
New rubber sleeves for runners
New injector seals
Cleaned injectors, all running very well, and opening at spec
CIS pressures all tested and all to spec
Throttle plate to spec
Throttle plate/plunger moves smoothly, lifting before starting doesn't help.
Smoke test showed no leaks
CSV working and not leaking
CSV micro switch working and adjusted correctly
New TPS from Porsche (which was a noticeably nice improvement, but not for starting)
Original WUR working to spec (which, with the TPS, works better than the 008,009 and 129 I've had)
One test showed 11V to CDI during cranking (12.4 when not cranking)
Timing spot on (with Pertronix)
Pulled out harness pin connecter a few times, but looked great.
Cleaned the ground near the CDI, but looked great.

By the way, here are the items from the list that HarryD provided a while back that are hard starting issues. All of them have other symptoms that would/could be happening. But none of them are here, except that one injector:

Leaks in intake system - nope, did smoke test, more than once.
Sensor plate not moving freely - sure seems to move freely - and lifting per Pete's test didn't change anything.
Sensor plate not set correctly - spot on
Fuel pump not operating - is working fine, with correct control pressure
Warm control pressure to high - pressure is correct
Fuel system leakage - none visible or smellable
Injector leaking, opening pressure low - one mentioned above, that about to replace.
Injected fuel quantities unequal - other than leak after turning off, all equal
Basic idle setting incorrect. Nope, spot on.

Here are the things listed in the blue Porsche Troubleshooting Guide:
System pressure drops too far and rapidly after switching off ignition (tendency for vapor bubbles to form) - to spec
Injectors leaking, or opening pressure too low (vapor bubbles) - maybe one, and now about to replace
Cold start system defective - not that I can see
Sensor plate stop too low. - spot on. Maybe I should raise it anyway?

We'll see after I replace that one injector.

No resistor on these years, but I remember working on 60's cars that had them.
You have done about everything that could be done, except the CO level. I had issues on mine due to dripping injectors. The fuel distributor piston shuts off the flow of gas, and line would lose it's fuel. I would turn the key on, lift the plate for a second to charge the lines and it would start right up.
As far as the sensor plate, if the front edge by the pivot is even with the lip enjoy the ride.
http://forums.pelicanparts.com/uploa...1714431318.jpg

Keep driving it. Put more fuel cleaner in the tank (might help, won't hurt).

Did I mention to keep driving it?

I've been driving it almost daily. But having to crank it 5-8 times to get it to start is just too wrong.

Ignition is your problem…….
 

If you are igniting your fuel on the first crank it would fire and run. But it takes too many attempts to get your motor to start. And this problem is not going to go away and will be worse as time goes by. What is your CCP? Have you tried to use an inductive light and confirm a strong the ignition signal? The spray patterns of the 7 injectors are very critical too. The more mist-like the easier to ignite. Pull the 6 spark plugs and take some pictures.

A regularly driven CIS motor should start and run all the time. Does this multiple attempts to start occur both cold and warm condition? Keep us posted.

Tony

What is your CCP?
System pressure: 4.55 (spec is 4.5-5.2)
Cold Control Pressure: 1.85 at 66 degrees. (spec is 1.7-2.15)
Warm Control Pressure:
Idle 3 (spec 2.9 - 3.1)
Part load: 3.7 (spec 3.5 - 3.9)
WOT: 3.1 (spec 2.1-3.1)
Leak down after 20 min: 1- 1.3 (spec 1)

Have you tried to use an inductive light and confirm a strong the ignition signal?
I used the light to check timing. It worked well. But I actually don't know how to use the light to check how strong the signal is.

The spray patterns of the 7 injectors are very critical too. The more mist-like the easier to ignite.
I cleaned them. Before and after, they sprayed beautifully - better even than the video where the guy showed how the cleaner worked.

Pull the 6 spark plugs and take some pictures.
Will do.

Does this multiple attempts to start occur both cold and warm condition?
Starts well when cold, though not as perfect as it used to.
Starts well shortly after shut off.
If it sits for 10 or 15 min, starting becomes an issue. And it doesn't get better for at least a few hours.

Huh? How long do you crank each time?

I don't know. 5-10 sec? Long enough to feel like nothing is happening at all. I keep letting it spin, then stop and go again 5-6 times until I get a very small burble of ignition. Then usually the next time after I get that initial burble, it does start.

I have tried many different ways, going back and forth between with and without throttle (to not use the CSV). And no pattern seems to be better. But I will say that when I keep doing it with throttle, I do start smelling gas, which I assume is just more and more CSV squirts.

I'm crossing my fingers that the replacement injector will cure it (it arrives Thursday). But otherwise, I'm not sure what to go back and check again. The normal culprits for this issue, the accumulator and return valve are new, and directly from Porsche.

Here, by the way is my car now - original paint/interior, very well taken care of over its life.http://forums.pelicanparts.com/uploa...1714492846.jpg

I know you tried this earlier, but I would re-try the starting fluid squirt before starting the first time. If it fires, then I think your CSV is not working. I know you tested it, but something is still wrong in that part of the starting sequence.

On the other hand, if priming it with starting fluid does NOT cause it to fire immediately, then I'm thinking that you are not getting spark initially, or the CSV might be delivering too much fuel and it's too rich/flooded.

Yeah, we are recovering the same ground, but I don't see other ways of proceeding.

Pete. Good points. I would add get the pictures if the plugs.

Jay,

Try to use a starting fluid when it struggles to start. If you have a POV, apply through it and push it down. Get someone to assist you. Or place some weight over the POV. A video would be helpful.

I will make you an offer and think about it. I like to test and investigate your fuel distributor, CSV, fuel injectors, etc. for FREE. And I will ship your parts back 2~3 days from receiving the package. I could do the tests anytime you are ready. Reducing the variables would help us better identify the culprit/s. This is for the fuel side. The ignition is another thing.

I like to test and confirm that these CIS components are not contributing to your START problem. Without testing these critical components, there are too many variables in the equation. And I won’t be offended if you say NO.

Tony

Update.

I sprayed starter fluid in for about 2-3 seconds. Didn't change anything.

When spraying the starter fluid, I was surprised to find that the POV does not seal when not running. When running, it is certainly sealed. There is a small but certain gap at the front. I tried putting a weight on it and then I taped it fully shut. Did not change anything.

Below is a picture of a spark plug. Bosch, WR5DP (platinum tip), which I got from the Porsche dealer. They all look the same. They are maybe 3,000 miles old. But I know that really not supposed to use platinum on older cars. And perhaps these are too cold for the engine. But this is what Porsche supplied, so I went with it. I just ran to my local auto store and bought some NGK replacements with copper tips. How they had them, I'll never know. But they are going in.

http://forums.pelicanparts.com/uploa...1714863028.jpg

Spark plug looks okay. A bit dirty, but not black.

I would start investigating poor spark or lack of spark at this point. Since you already have at least one plug out, plug the wire onto it and ground it to the engine. Then crank and see if it gives consistent bright spark.

Possible hypothesis: Coil going bad. Check the primary and secondary resistances and post them here.

Let me ask again: How does the car run after you get it started? Are there any stumbles or misses, particularly at high RPM and load?

Changing spark plugs didn't change anything - and I might go back to them.

But if it is spark, then I would think that would not mean it starts ok when cold, bad after the first 10-15 min, and then stays bad for a few hours.

I had one though. I seem to recall that the plunger in the fuel distributor can get sticky, which would mean that the starting air suction pulling up the plate is not pulling it as high, which would mean the car is leaner then.

BUT, it does feel smooth when I push it up, and it falls down pretty much immediately. So I'm not thinking that is it. And it doesn't seem to explain it anyway.

As to testing the spark and the coil, I did swap coils to an old coil I had (actually the original factory one). It didn't make a difference. But I no longer recall why I changed coils decades ago anyway. And I thought a failing coil fails at high rpm not starting. But I could be wrong.

And I also thought it was not good to test the spark on a CDI system. But I'm happy to try it if I can.

There is one other factor that I was just realizing. I might have mentioned it before. For all the years I've owned it, as I recall, when I first turn on the ignition, I'd hear the high pitched fuel pump. And I'd wait until it dropped in sound. Kind of like a fuel bowl filling. But that is not happening now. I actually figured it was because the check valve and fuel accumulator were keeping everything full. But now I'm wondering if it is a sign of something else.

It seems to me that either (1) the pressure is always being maintained, or (2) the pressure can never get fully up. I think it is hard to believe that the pressure is always maintained. But given that the pressures all test to spec, I have to think that they are holding back the gas and it should still firm up and change pitch.

I wonder if I should clamp off all the return hoses for the various pressure relief valves. Maybe one never shuts. But again if that were the case, I'd figure my fuel pressure readings would never be to spec.