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Might do one more test that will shed more light on the problem. Before replacing the wire, next time it doesn't start do a jumper wire around the neutral safety switch. The '68's are made like my '67 and the grease does dry out inside the slider switch and the hard grease can cause intermittent contact. Not too bad to bend back the tangs and get inside to clean out and replace the old stuff with a silicone grease.
 
Discussion starter · #25 ·
Might do one more test that will shed more light on the problem. Before replacing the wire, next time it doesn't start do a jumper wire around the neutral safety switch. The '68's are made like my '67 and the grease does dry out inside the slider switch and the hard grease can cause intermittent contact. Not too bad to bend back the tangs and get inside to clean out and replace the old stuff with a silicone grease.
Thanks, I tried that, didn't make any difference.
 
I ran the jumper wire from hot side of nuetral safety switch harness to S terminal on starter. Did the same thing. I had the neutral switch unplugged ruling it out. It would still just click at times,other times it cranked fine?
Then my next guess and what I would swap out, is the starter solenoid if all your battery connections appear good and are tight. A starter solenoid will act like that wen going bad.
 
Discussion starter · #29 ·
Then my next guess and what I would swap out, is the starter solenoid if all your battery connections appear good and are tight. A starter solenoid will act like that wen going bad.
The starter in the car is new. I got another solenoid and already tried it. Made no difference. Is there a way to check the ignition switch?
 
The starter in the car is new. I got another solenoid and already tried it. Made no difference. Is there a way to check the ignition switch?
You jumped the ignition switch when you put the 12V to the "S" terminal, so that would almost rule out the ignition switch. You still had the issue.

By hot wiring to the "S" terminal, it simply narrows it down to starter, battery cables, battery.

Does the engine have the ground strap from the head to the firewall and from the engine to the frame? The negative gound battery cable should go to a stud on one of the head bolts, do you have that? There also should not be ANY paint under any ground. Sometimes when parts re painted, those places where the grounds attach are not cleaned to bare metal. The paint can act as an insulator.
 
Discussion starter · #31 ·
You jumped the ignition switch when you put the 12V to the "S" terminal, so that would almost rule out the ignition switch. You still had the issue.

By hot wiring to the "S" terminal, it simply narrows it down to starter, battery cables, battery.

Does the engine have the ground strap from the head to the firewall and from the engine to the frame? The negative gound battery cable should go to a stud on one of the head bolts, do you have that? There also should not be ANY paint under any ground. Sometimes when parts re painted, those places where the grounds attach are not cleaned to bare metal. The paint can act as an insulator.
Jim
Sorry but I don't understand how I ruled out the ignition switch? I unplugged the neutral safety and jumped from that harness to the starter. I still used the key and starter switch to test it. Starter switch was still involved?
Thanks
 
Discussion starter · #32 ·
Jim
Sorry but I don't understand how I ruled out the ignition switch? I unplugged the neutral safety and jumped from that harness to the starter. I still used the key and starter switch to test it. Starter switch was still involved?
Thanks
Jim I also cleaned the paint and bolts of all ground connections and braided ground straps are new and in place.
 
Jim
Sorry but I don't understand how I ruled out the ignition switch? I unplugged the neutral safety and jumped from that harness to the starter. I still used the key and starter switch to test it. Starter switch was still involved?
Thanks
OK, got it. Jump a wire directly to the solenoid "S" lug. The "S" lug on the solenoid is the wire that electifies/enegizes the starter.

Use a jump wire with an alligator clip on it to attach directly to the "S" terminal. Do not touch anything else. Then simply touch the other end to the +Battery post. It will activate the starter and the engine will spin. If you can do this a couple times successfully, then you know that the solenoid/starter are fine.

If you don't have any issues, then that would mean that the problem is between the "S" terminal wire (Purple) and going back to the ignition switch.

Here is the 1968 Wiring Diagram. Follow the Purple (PPL)/SOL wire. It comes off the back of the ignition switch plug, runs through the neutral safety switch, and on out to the firewall plug and to the starter.

I assume in your description jumping the Neutral Safety Switch that you by-passed it and ran a jumper wire from the ignition side of the switch to the out going side of the switch, thus eliminating it completely from the circuit. Then you hit the key and sometimes it started and sometimes not.

Since you tested the starter/solenoid with the jumper wire previously mentioned, and you by-passed the Neutral Safety Switch, that leave the Ignition Switch.

Find the Purple wire at the ignition switch plug and you should be able to use a 12V hot wire and energize the Purple wire from that point and the engine should crank. If it does each time, then it is the Ignition Switch. The small "points" that the inner arm makes contact with do wear down/out.

If you need a new Ignition Switch, make sure it is for a GTO and not a Tempest. I found that out myself. The lugs/spaded on the back of the switch are different in their positions. So you want a switch that will match yours so it will fit back into the plug. My Lemans used the GTO type switch and the "advertised" will fit GTO was incorrect.



Building Rectangle Font Parallel Schematic
 
Discussion starter · #34 ·
Thank you Jim. I will try a hot wire to the ignition plug purple wire.I am assuming I do not need the switch plugged into the harness at this time? I have a laminated wiring diaghram, and also a service manual.
 
Thank you Jim. I will try a hot wire to the ignition plug purple wire.I am assuming I do not need the switch plugged into the harness at this time? I have a laminated wiring diaghram, and also a service manual.
Yes, that is what I am assuming and would do next. My thinking is to energize that wire at the plug which should be the same as when you turn the key to the "Start" position. The switch simply directs the power to "Start" which will energize the solenoid wire AND the coil (so the engine may want to start) as this is the 12V that goes to the coil to provide the voltage for a good start with points. Then the switch gets snapped back to "RUN" and the solenoid wire gets shut down, the 12V to the coil shuts down, and the 12V travels from the ignition switch through the resistor wire hooked to the coil to drop voltage to 7-9 volts so you do not burn points. So IF you still have points, you will have 2 wires connected to the + side of the coil. If using an electronic system, then you have to source a 12V wire and by-pass/eliminate the resistor wire. But in either case, you are seeing if the 12V from the iginition switch plug will turn the engine over.

(y)
 
Discussion starter · #36 ·
Yes, that is what I am assuming and would do next. My thinking is to energize that wire at the plug which should be the same as when you turn the key to the "Start" position. The switch simply directs the power to "Start" which will energize the solenoid wire AND the coil (so the engine may want to start) as this is the 12V that goes to the coil to provide the voltage for a good start with points. Then the switch gets snapped back to "RUN" and the solenoid wire gets shut down, the 12V to the coil shuts down, and the 12V travels from the ignition switch through the resistor wire hooked to the coil to drop voltage to 7-9 volts so you do not burn points. So IF you still have points, you will have 2 wires connected to the + side of the coil. If using an electronic system, then you have to source a 12V wire and by-pass/eliminate the resistor wire. But in either case, you are seeing if the 12V from the iginition switch plug will turn the engine over.

(y)
Thank you. I have a new hei distributor. I’ll unplug it when attempting this. The motor will start right up when cranking. Just doesn’t crank each time. I will let you know. Thanks for your advice Jim.
 
Discussion starter · #37 ·
Thank you. I have a new hei distributor. I’ll unplug it when attempting this. The motor will start right up when cranking. Just doesn’t crank each time. I will let you know. Thanks for your advice Jim.
Jim

Problem solved. I removed the purple wire from back of ignition switch and ran a new wire from the switch terminal S to the starter solenoid. Cranked over several times in a row with no solenoid clicking. So now I will eliminate the old wire and run a new one. Thank you Jim for your time and knowledge. It has a new 461 stroker that I'm anxious to get on the road.

Also want to thank lust4speed, Jim K, rockdoc and geeteeohguy and anyone else I may have missed for sharing their knowledge also. This is a great group.
 
Where do I look for fusable links??
I have another thread called '70 not starting' and seem to be having similar issues.
have brand new Optima battery
Starter is 1 year old from Napa
Throughout the starter and alternator circuits... they look like rubber barrels/ cylinders in the middle of the wire. They often burn out without it being visible... You can test/ check them by running a continuity test on the wire... but if they're intermittent, that can be a pain.

Electrical wiring Wood Twig Wire Gas
 
My 70 Corvette had them at the horn relay, and the primary one for the charging circuit looked fine, but was not. When driving the car, it would just shutoff, out of no where! then wouldnt restart. I actually think it's why I got the car so cheap!

Anywho, a $2 wire off Amazon and I was back in biz
 
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