CIS (82 SC) Cold Start

[ianc]

What will starting fluid do? It might make it run for a bit, but if there is a problem, cold start or otherwise, it's not going to fix it.

ianc

[ruf-porsche]

Originally posted by ianc
What will starting fluid do? It might make it run for a bit, but if there is a problem, cold start or otherwise, it's not going to fix it.

ianc

If it doesn't start with starting fluid, maybe it not a fuel problem, but an ignition problem. You have to determine the problem in order to fix it. Some time the only way to determine the problem is through the process of elimination.

Cold start valve is only used when you first go to start the engine. Afterward, the thermotime switch cuts out the cold start valve. If the engine tries to start with the starting fluid, after the first time the engine run, the cold start valve is no longer required to start the engine.

[ianc]

If it doesn't start with starting fluid, maybe it not a fuel problem, but an ignition problem.

He already said he has spark. Check the 1st post.

ianc

[Gunter]

Originally posted by twopoorsche
Thanks for the tips. I've always been able to hear a whirring sound on CIS cars when the ignition was on; I thought that was the fuel pump. I'll pull the airbox cover off and lift the lever and see what happens.

I do not believe that it is a fuel pump relay (I swapped it with one of the black ones, but maybe that would not work), and my experience with cold start valves is that CIS engines will at least try to start on a warm day (80 degrees plus here) even with a bad cold start valve. This car has NO indication of wanting to crank.

99% that I am not getting fuel, but I am still not sure why.

I'd swap the red relay from my '88, but it is in the shop!

This car has no indication of wanting to crank

It doesn't crank? Or it turns over but doesn't start?

If it doen't crank, your battery is suspect along with the relevant wiring to the starter.

A black relay will work just for a testing the pump. Pull one of the injectors while lifting the air sensor plate. Pick an injector that's already loose, spray a little WD-40 on the O-ring, then use two open-end wrenches to pray STRAIGHT up. There should be a fine spray with the pump running.
Careful; have a fire ext. handy.
Let us know what you find.

[ruf-porsche]

Originally posted by ianc
He already said he has spark. Check the 1st post.

ianc

So if he has spark and he sprayed starting fluid into the airbox, why doesn't it start?

[cantdrv55]

How long can the engine continue running if there's no fuel being delivered but was able to start using starting fluid? Or, would the engine even start at all?

[ianc]

So if he has spark and he sprayed starting fluid into the airbox, why doesn't it start?

That's what we're trying to figure out.

How long can the engine continue running if there's no fuel being delivered but was able to start using starting fluid?

A few seconds at best...

ianc

[twopoorsche]

Originally posted by ruf-porsche
Have someone spray the starting fluid into the airbox intake snout while you crank the engine.

The last time when you spray the starting fluid into the toilet seat was it up or down?

Did the engine try to start or did it just crank?

Starting fluid was my first inclination, but a mechanic talked me out of it due to air box concerns. However, while I am getting a test light to come on at the distributor while engaging the starter, that is not to say I am getting an adequate spark.

Anyone want to comment on the use of starting fluid with a CIS airbox?

For the record I always put the toilet seat down. My wife taught me that!

[Lorenfb]

This thread has become very confusing. These should be the troubleshooting
steps:

1. The engine must crank over at a good RPM.
2. The coil wire to the distributor must produce a spark of about 25mm
to the engine case.
3. The fuel pump must run when the sensor plate is moved.
4. The system pressure must be at least 60-70 psi. The control
pressure (cold) should be about 25 to 30 psi.
5. The spark plugs must NOT be saturated with fuel, i.e. from
cranking without a spark. This is a common no-start issue on
911SCs.
6. Check the cap for moisture (shielded caps a problem). Then check
the rotor. Then check that the spark at the plug is strong. Don't
assume that a good coil spark is a good cylinder spark.

If all of the above are O.K., then check the mechanical elements of the
engine, e.g. compression, or ignition/valve timing.

[cantdrv55]

Originally posted by twopoorsche
Starting fluid was my first inclination, but a mechanic talked me out of it due to air box concerns. However, while I am getting a test light to come on at the distributor while engaging the starter, that is not to say I am getting an adequate spark.

Anyone want to comment on the use of starting fluid with a CIS airbox?

For the record I always put the toilet seat down. My wife taught me that!

Where are you located? Maybe you can enlist the help of Pelicans close by.

[ruf-porsche]

Originally posted by twopoorsche
However, while I am getting a test light to come on at the distributor while engaging the starter, that is not to say I am getting an adequate spark.

Pull a plug wire and either hold it next to the engine or insert a spark plug into the plug wire and ground the plug and see if you have a spark.

Just because you have power going to the dizzy doesn't mean that you have a spark.

[Paulporsche]

Have you checked your battery output? You say your car sat for a week. Sometimes w/ these cars, you may have enough power to run the fuel pump but not enough to actually start the engine.

[twopoorsche]

Originally posted by Lorenfb
This thread has become very confusing. These should be the troubleshooting
steps:

1. The engine must crank over at a good RPM.
2. The coil wire to the distributor must produce a spark of about 25mm
to the engine case.
3. The fuel pump must run when the sensor plate is moved.
4. The system pressure must be at least 60-70 psi. The control
pressure (cold) should be about 25 to 30 psi.
5. The spark plugs must NOT be saturated with fuel, i.e. from
cranking without a spark. This is a common no-start issue on
911SCs.
6. Check the cap for moisture (shielded caps a problem). Then check
the rotor. Then check that the spark at the plug is strong. Don't
assume that a good coil spark is a good cylinder spark.

If all of the above are O.K., then check the mechanical elements of the
engine, e.g. compression, or ignition/valve timing.

1. This is happening.

2. I can check this.

3. This is happening.

4. Pressures were checked recently, car was running and starting perfectly until this abrupt malfunction.

5. I doubt that this is the problem. The sudden onset would not so indicate.

6. Not the problem.

A "mechanical elements" problem would be surprising, given that the car went from running and starting perfectly to not starting simply by sitting in the garage for 6 days. The type of problems you suggest would likely show prior symptoms.

I have owned 8 911's and have had a myriad of problems. This one is strange, unless it is an ignition problem, and it is getting at least some spark.

[cantdrv55]

Please let us know what does fix your SC. This thread will help another Pelican in the future.

[Lorenfb]

"2. The coil wire to the distributor must produce a spark of about 25mm
to the engine case."

Sounds like this hasn't been fully ckecked, right? This is a very key test.

Again, these engines flood easily with weak sparks, so check & clean
all the plugs. Also, if the plugs are dry then maybe it's a fuel problem.

[Gunter]

Thanks for the reality check, Loren.
twopoorsche: Testlight? DO NOT use a test light on the distributor to determine proper function; the CDI system is not the conventional ignition from olden days. A test light may be good for an old Ford, but you can harm your CDI module with this crude approach.

Test light on the Bosch CDI ranks along with testing the Alternator by disconnecting the battery with the engine running; still runs? then the alternator is o.k. (But now I wonder why the diodes burned out?)
Some people never made the mental conversion from Generator to Alternator.

Anyway, if you have had that many Porsches, Loren's advise on how to troubleshoot a non-start should be familiar. Do it systematically through elimination instead of guessing and jumping all over getting nowhere.
When an engine gives problems, it's either fuel, or ignition (electrical), or mechanical. You mention "Not cranking" but you also "It just turns over"???????
Try Loren's advise and let us know what you find.
And, get a Bentley Repair Manual; it's a great help.

[twopoorsche]

Originally posted by Gunter
twopoorsche: Testlight? DO NOT use a test light on the distributor to determine proper function; the CDI system is not the conventional ignition from olden days. A test light may be good for an old Ford, but you can harm your CDI module with this crude approach.

Test light on the Bosch CDI ranks along with testing the Alternator by disconnecting the battery with the engine running; still runs? then the alternator is o.k. (But now I wonder why the diodes burned out?)
Some people never made the mental conversion from Generator to Alternator.

Not sure I agree with you. The key is to not ground the test light. It will still light up if not gounded. Why would it harm a diode? If you ground the test light, then you would be correct.

[Lorenfb]

"Not sure I agree with you. The key is to not ground the test light. It will still light up if not gounded. Why would it harm a diode? If you ground the test light, then you would be correct."

1. Gunter is correct about NOT using a testlight on a CDI coil.
The low resistance of the testlight may cause an execessively high current for
the internal SCR device damaging the CDI unit.

2. The testlight will NOT light if it's not ground. The pulse from the CDI is
less than 200us. Even if grounded, you'll never see a flash. So the test
will be a waste.

[Gunter]

Originally posted by twopoorsche
Not sure I agree with you. The key is to not ground the test light. It will still light up if not gounded. Why would it harm a diode? If you ground the test light, then you would be correct.

The big electronic brains on this board can explain why not to use a testlight on the coil in detail; Bottom line is: NO TESTLIGHT!
If you want to know how to troubleshoot/test your CDI, do a search here.

Burning out diodes is referring to the alternator, not the CDI.
There are still people who believe that disconnecting the battery while the engine is running is the way to see if the alternator/VR works.
I am just mentioning it as one of those practices that don't seem to die out; like a testlight on the coil with a CDI system.

Anyway, follow the steps suggested by Loren and let us know what you find.

[twopoorsche]

Pulled a plug. I am gettng visible spark. Plug was dry when I pulled it, and the engine had been turned over for 30 seconds or so before pulling the plug.

Reinserted plug, and used a liberal amount of starting fluid. White smoke from tailpipe, but NO indication of starting.