Ignition/Electrical (?) Problem

[Paul Sachelari]

Hi all,

I have recently revived a C that had been lying dormant in a neighbor's garage for over three decades. I did all the normal stuff you'd need to do to get a car that has been sitting, back on the road, but didn't touch the electrical system since it was all seemingly working fine. After driving the car pretty much daily on local trips, I recently took it on its first really long hard drive on a classic car rally in Northern California and Nevada (up and around Tahoe - photo attached). It drove great... mostly. Here is the problem:

One morning, I came out to start the car, and it would not turn over. Turn the key to "starter" and nothing. The idiot lights came on, but when I turn to start, they just dim. Nothing from the starter. At that point, I was in the mountains around Tahoe, so I thought maybe the battery somehow was not putting out enough juice due to sitting in the cold outside overnight. I had some friends help push start the car. It started up fine. I drove it hard the rest of the day with no issues, including re-starting it at various times.

On the way back home, I drove for several hours at highway speeds non-stop. Within a few miles of my house, the motor sounded like it was missing, or there was some backfiring through the carbs. Thinking it was getting too warm or vapor locking, I slowed down a bit to see if it would abate, to no luck. I pulled off the freeway, and as I let off the gas, it stalled. At that point, it would not re-start, and was doing the same thing (idiot lights on, no starter, just dimming lights with the ignition in "start" position).

After a tow home, it is still doing the same thing with a cold engine - it will not crank at all (idiot lights go on, but no ignition or starter cranking with the key in "start" position). I have checked the battery - still 6 volt system - and it measures 6.3 volts. I charged it again, just to be sure, and re-installed with tight positive and ground connections at the battery, with no luck. I also jumped the negative lead to the frame, in case the negative (original) battery cable was somehow not connecting. That did not help.

I'm thinking that maybe the ignition switch is not working? Any suggestions on other things I should check?

Thanks in advance,
Paul
Oakland, CA

[Paul Sachelari]

I should also mention, that at the same time that the car was having trouble on the freeway, the tach started also acting erratically. I'm not sure if the two have any connection, but I thought this could be a relevant detail.

[John Clarke]

Hi Paul
Could be the Starter Solenoid getting stuck. Give it a few light taps with a hammer. Replace if it then starts
Possible Coil or condensor problem
Jay

[Mike Wilson]

Electric tach? Check continuity from gauge to coil.

Mike

[Pete Indelicato]

backfiring?--fuel delivery issue?

[Paul Sachelari]

I don't think it is fuel or the coil since the car won't turn over at all. My thinking is that it should at least turn over, even with a bad coil or fuel pump... it just wouldn't start if they were bad. Since the motor won't even crank, that seems to point to some sort of electrical problem. Also, since it was running, and died while driving, I'm thinking the starter or solenoid is not going to be the problem, unless somehow they are part of the circuit in such a way that everything dies if they have a failure.

[Mike Wilson]

Another possibility is a bad ignition switch or a wire to or from it.

Mike

[John Clarke]

Hi Paul
Ref your running problems I think with Coils that are starting to fail, the car Will start, but as the Coil heats up it starts to fail. As You know Most faults are fuel or electric related and Ref the Non Start issue, Have you whacked the Solenoid yet ?
Let us know what you find.
Regards Jay

[Doug McDonnell]

Clean and reattach both ends of the transmission to body ground wire. Then follow the troubleshooter matrix: https://www.cyberwerkstatt.com/Members_ ... ooting.htm

[David Jones]

It does rather sound like a ground cable open circuit or main power cable. I would examine both very carefully end to end.

[John Brooks]

Sounds like the Key switch 50 has a bad internal contact. I had a similar problem on my 912 a few years ago, I did not have a spare Key switch so I put a starter by pass relay on the starter. I ran an extra wire up into the engine compartment with a momentary push switch on the regulator bracket. . Use the B+ on the voltage regulator to the switch and down to the relay and connected it to the new relay where the 50 from the ignition connects to the relay coil.. Now I can turn on the key, operate the starter for the back and start the engine. I do 356's similar on Voltage regulator also. ( also early 912/911 have a unconnected female spade yellow wire by the voltage regulator that activates the starter solenoid )

You mount the momentary push switch on a small bracket on the Voltage Regulator mount and run a wire down to the bypass relay. A short wire to the switch from B+, and then from the other contact down to the relay, Now you can use the key or start the car for the back. On cold starts after a long time sitting, being able to work the carbs from the back makes starting dry carbs much easier. Plus you can bump the engine around with the AUX switch when working on the engine. Every time I install a started relay or have someones engine out I put one in the car.

The 6V relay are about S15.00, not too hard to make or I believe several members sell kits. The bypass relay will save the key switch from the solenoid current, and the AUX starter switch in the engine compartment is easy and will save you on the side of the road some day.

[Jules Dielen]

I would start with checking both ends of the ground strap at the battery, see if they are clean and tight and also verify the positive clamp is clean and tight. Corroded or loose connections do weird things

[Jon Schmid]

I guess my earlier post got nuked. Check the ignition switch or the the condenser. Those have both stopped me cold on the road. Good luck!!

[Hugo Karasawa]

The car was dormant for three decades, you might have several problems.
Check system by system. Finish one and go to the next one.
Starter system , switch, solenoid starter, grounds.
Ignition System, switch, coil, distributor, condenser, points, cables spark plugs, timing.
Fuel system, Tank, lines, filter, pump, carbs.
Valve train.
Do not add extra components before the initial problems are solved.

[Mark Roth]

I had an ignition switch go out during a Chattanooga holiday drive. Had to rig up a jumper to get back. Fuel system problem sounds like fuel pump. Been there, done that on the way to the Durango holiday. An electric pump in series is a good mechanical pump backup.