Difficult case of no spark. Experts wanted!

[timmy2]

For Daves test ,the top fuse should be constant 12 vdc. The lower one is fed by the same circuit as the CDI power supply is on.
If a different 12 v supply fixes the problem, then go up front and move the red wire from terminal 8 to terminal 7 and see if the problem goes away. (Alternatively jumper terminal 7 to terminal 8)
If it does, it is the fuse block internal jumper. If it doesn’t it may be the ignition switch.

[Jeremy911T]

Originally Posted by mysocal911

That's the source of your problem. That power source normally comes from your ignition switch.



That's good.



Actually, that measurement should be between the B pin and the C pin with the CDI disconnected.



So it looks like you've had an intermittent/poor power source to your CDI pin B.
Before troubleshooting the power problem, use a jumper wire to power the B pin by
connecting the wire to one of the fuses on the left side near the big engine harness
connector. Hopefully, your engine should start.

You are the man!!!!! I jumped the B pin from the fuse and it started right up. I noticed that the tach wasn't working so that must be tied into that B terminal somehow. The car wouldn't stop until I disconnected the jump wire. So what are some possibilities on the poor power source to the CDI?
Thanks for all of your help!

[timmy2]

Read my post above yours to troubleshoot the feed to the CDI power.
Could also be as simple as a poor connection in the 14 pin connector below the CDI.
Pull it apart and see if there is any corrosion or even just loose.

[Jeremy911T]

Thank you! I will check these

[HarryD]

Originally Posted by Jeremy911T

Hi Harry,
I just posted the results from the tests I ran. Any thoughts?

Looks like you are on it. Listen to Timmy2

[timmy2]

Also, check the ignition 6 pin plug under the dash is fully inserted. Farthest one to the right side .

[Jeremy911T]

Originally Posted by timmy2

Also, check the ignition 6 pin plug under the dash is fully inserted. Farthest one to the right side .

Hi Dennis. The 14 pin is clean, the 6 pin under the dash is fully inserted and the jumper from 7 to 8 didn't fix the problem. So it looks like it is the ignition switch. Anything else I should test before I tackle the electric portion of the ignition switch? Thanks again for all of your help?
Jeremy

[timmy2]

With the key in run, do you have 12 vdc that will light a test lamp style voltage tester on the same fuse terminals 7&8?
If no, it is likely the ignition switch.

[Jeremy911T]

Hi Dennis,
Thanks again for all of your help. I think I have almost narrowed it down but need just a little more help to get to the finish line. I decided to give all my connections a through cleaning as I noticed a little corrosion. I started under the bonnet and even though there was conductivity in all of the fuse connections I cleaned with a combo of a wire brush, files, CRC electronic cleaner and then place dielectric gel. I noted on the fused side of 7 & 8 a fair amount of corrosion within the brass fittings. I then moved to the back and did the same thing. I opened up the two 14 pin connectors and cleaned out the male and female ends, all the connections on the speed switch, rear defogger and the other relay. I had already done the CDI connections. I then checked the ignition switch, pulled off the plug to inspect. All looked good, but I placed some dielectric gel for good measure. I hooked everything back up and to my surprise, the CDI was singing like a choir boy. I go to start up the car and.....it won't turn over. I was about to rip my hair out but I'm already bald. I had previously had a difficult starting problem, but cleaned and placed dielectric on the transmission ground strap, the 2 battery straps and all of the wires coming off the 2 batteries and that solved that problem. I woke up this morning and went though everything again, checking all my connections, removing and reinstalling the 14 pin connectors. After doing this I turned the key to the car and.....it started. I was very happy but...I turned it off and tried to restart it and nothing. I was then thinking an intermittent starter switch problem. I again pulled off the started switch plug. It was getting 12 volts at terminal 30. Plugged it back in.

Then I checked the voltage at the (2) 14 pin connectors in the engine compartment. I don't know the correct names but I think the more forward connector is the Chassis 14 pin and the more rearward the engine 14 pin.

The chassis (forward) 14 pin had no volts at any of the connections with the car key off. With the key in the on position, there was 12 V at 5,12, and 13. When I attempted to "crank" the engine the 1 (yellow solenoid wire) went to 12 V.

The engine (rearward) 14 pin had a constant 12V at 14. The number 1 (yellow solenoid wire) didn't change when I attempted to "crank" the engine but stayed near 0 volts.

I then go to hook everything up and now it is starting again. I started and stopped it 10 times and now it is starting every time.

Questions:
1. What does the 14 pin voltage data tell you?
2. The fact that the chassis (forward) 14 pin connector #1 connection reliably went to 12 V when I attempted to start the car tell us that the ignition switch is ok? It would do this reliably even when the car would not turn over.
3. Is it safe to say the spark problem was caused by resistance due to corrosion. The CDI has been singing loud since I cleaned all the connections.
4. Why do you think the car all of a sudden wouldn't crank? This hadn't been a problem until I cleaned up all the connections. Could it be due to manipulation of the wires on the rear engine harnesses or something to do with the speed switch or another switch on that panel of connectors in the back?
5. The one thing I haven't done is clean the connections to the starter and the solenoid. Could this have something to do with it?
6. What are the 3 relays on the panel. I have no idea what the most forward one is, but I think the middle is the defroster, and the most rear is the speed switch. Could something in the speed switch cause the intermittent starting problem or the findings of the solenoid wire readings above?
7. Is it normal for the engine (rearward) #1 yellow solenoid connection to stay near 0 when attempting to crank the engine.

I am certainly glad it is starting, but I worry about reliability. I think Hagerty's is going to balk at my next tow request.

I have included a picture of the relays and connections in the engine compartment. I have now yet secured them back up but have grounded the plate.

Thanks for any input,

Jeremy

[timmy2]

Rear 14 pin to engine is notorious for the yellow wire connection needing attention.
Sounds like you have addressed all of the connections and should be good to go until/if any corrosion builds up again. All your measurements sound correct.
At a minimum, you know where to look for issues should it act up again.

A small Dremel wire wheel bit spun lightly in the female contacts does a good job to clean.
Try some De-Oxit D5 as a cleaner and final treatment as well. (Good stuff for contacts, cleans and lubes and preserves)

Great job going through everything that is in the circuits.
Happy motoring.

[timmy2]

Most forward unit is the remote voltage regulator for the alternator.

[Jeremy911T]

Just an update. I got my baby back on the road! Being new at the air-cooled 911 fraternity, I certainly learned a lot of things. Specifically:

1. Old cars can get corrosion of the wires and connectors. Mine was restored in the late 90's, has less than 2000 miles since restoration, was always stored in a climate controlled garage, and never saw the rain. I figured the wiring would be free of corrosion. I was wrong! The two issues I had with the car, wouldn't turn over and no spark, were a direct result of corrosion. Upon close inspection, there was corrosion of the 7 and 8 connections of the top bonnet fuse panel that caused conductivity issues with power getting to the CDI. After I cleaned these up, the CDI sang loud and clear and produced spark. I also traced the dreaded yellow wire to the coil. There was corrosion on the engine (rear) 14 pin connector. I cleaned this up paying special attention to the 1 pin and it cranked over like new. I subsequently cleaned up every wire and connection visible in the bonnet, engine compartment, starter, and ground straps. I found corrosion on all of those areas. Reading through the forum posts, there is a tendency to chase after the things that are less likely the cause of issues. I was convinced I had a ignition switch and starter problems. I had those ordered and could have spent a lot of time, money and frustration changing out those parts. The sage people on the forum echo this throughout.

2: What a wonderful resource this forum is! Timmy2 (Dennis) and HarryD held my hand through this process and seemed genuinely happy to help a novice that asked too many irrelevant questions. A huge thank you to them and Pelican for supporting the site!

[HarryD]

Great news!!!!


Glad to help. Many here have helped me over the years and I am just paying it forward.

[mysocal911]

Originally Posted by Jeremy911T

Just an update. I got my baby back on the road! Being new at the air-cooled 911 fraternity, I certainly learned a lot of things. Specifically:

1. Old cars can get corrosion of the wires and connectors. Mine was restored in the late 90's, has less than 2000 miles since restoration, was always stored in a climate controlled garage, and never saw the rain. I figured the wiring would be free of corrosion. I was wrong! The two issues I had with the car, wouldn't turn over and no spark, were a direct result of corrosion. Upon close inspection, there was corrosion of the 7 and 8 connections of the top bonnet fuse panel that caused conductivity issues with power getting to the CDI. After I cleaned these up, the CDI sang loud and clear and produced spark. I also traced the dreaded yellow wire to the coil. There was corrosion on the engine (rear) 14 pin connector. I cleaned this up paying special attention to the 1 pin and it cranked over like new. I subsequently cleaned up every wire and connection visible in the bonnet, engine compartment, starter, and ground straps. I found corrosion on all of those areas. Reading through the forum posts, there is a tendency to chase after the things that are less likely the cause of issues. I was convinced I had a ignition switch and starter problems. I had those ordered and could have spent a lot of time, money and frustration changing out those parts. The sage people on the forum echo this throughout.

2: What a wonderful resource this forum is! Timmy2 (Dennis) and HarryD held my hand through this process and seemed genuinely happy to help a novice that asked too many irrelevant questions. A huge thank you to them and Pelican for supporting the site!

It's unfortunate that a lot of time and effort was wasted on your part the result of misinformation in this thread, not withstanding your having a good at the time CDI unit rebuilt.
It wasn't until post 20 where the suggestion was made to jumper 12V to pin B of the CDI unit that the engine started and you posted (post 22);

"You are the man!!!!! I jumped the B pin from the fuse and it started right up."

Glad our efforts were productive.

[Jeremy911T]

Thanks Dave, Sorry I didn't mention you specifically. That was definitely the turning point! Let me know when you make it down to Laguna Beach. Lunch is on me.

[mysocal911]

Originally Posted by Jeremy911T

Thanks Dave, Sorry I didn't mention you specifically. That was definitely the turning point! Let me know when you make it down to Laguna Beach. Lunch is on me.

Thanks for the offer. I'm often in southern Orange Country helping Porsche repair shops troubleshooting.
If you need any personal help in the future, just email, I might be near you working.