Zed Head

Just realized that this is not very clear. "Connected" what between the two big posts? Why did you have to touch 12V to the solenoid pin if you had a remote starter, with a button? A typical remote starter does all of that for you. Does "removed everything" mean everything, all of the wires to the remote starter and the wire to the solenoid pin? If so the ignition relay is fine. The simple way to test the ignition relay is to measure voltage at coil positive after you turn the key on. And, you should have only needed to touch 12V to the solenoid wire with the key on to get the engine to crank, and start. Cliff/site - if the engine cranked and started then the positive cable and the ground have to be okay. The solenoid grounds through the starter motor mounting bolt just like the motor does.

The starter solenoid power wire does not pass through the ignition relay. You bypassed the ignition switch and the inhibitor relay. The cranking circuit is completely separate from the ignition circuit. You have a cranking problem, not an ignition problem.

The one in my car crumbled when I pressed on the wrong area. Unless a used one came from a garaged car I don't see why it would be any more durable, they all get baked from the roof heat. That $25 replica seems like a good bet. It's an odd color though.

FSM wiring versus Revision N wiring.

I just looked at the 1977 FSM wiring diagram, the one in the back of the book, and realized that what I thought was yellow with a black stripe is actually supposed to be black with a yellow stripe. Also realized that Revision N from the Download area shows a "seat belt relay starter relay" but the FSM shows an inhibitor relay. And the connections are of a different shape. I think that this has been discussed before and that's why there are there is a Revision N. Anyway, the fact that it started and ran, above, indicates that the ignition relay is working properly. It also shows that starter and solenoid are working properly. I would guess that the wire at the connector from the ignition switch would be the same color as the wire at the starter solenoid. Good luck.

Click this link, type details in the box, then click Save. I know it doesn't makes sense that Profile data is in the Account Settings area but that's where it is. https://www.classiczcars.com/settings/signature/

I would check power to the seat belt relay on the yellow/black wire. That's the power that comes from the ignition switch. If you have power there then you can assume the ignition switch is good. Separate in your thinking the starter solenoid wire and the ignition relay. You've already saved yourself the effort of removing the starter. Forgot the picture. Haven't you bypassed this already? -

Edit - replying to SteveJ's comment... Not clear what you mean. This is about power on the yellow/black wire to the starter solenoid. He says his starter does not turn. If he has an automatic, then focusing on the seat belt relay would make sense.

The ignition relay is not involved in the starter motor operation. The starter motor solenoid circuit varies depending on vehicle. You don't have any signature details so it's not clear what you're working with.

You can also take a piece of wire and connect it to the solenoid small terminal then touch the other end to the battery positive post. A poor man's remote starter switch. Cliff/site's suggestion is the quick and easy way, but using a piece of wire adds some convenience. Supplying battery power to the small solenoid terminal is exactly what the ignition wire does. It will actuate the solenoid which will move the plunger and cause the starter to turn and the gear to engage the flywheel or flex plate.

No point in working on the starter if it's not getting power from the wire.

This might be one of them.

The "condenser on the negative post" might have come from a solution I developed in the past for a tachometer problem, and have recommended for the occasional odd tach problem, as a last resort. In my case, the needle would just sit and quiver until the condenser/capacitor was attached. My general theory was that it absorbed voltage spikes/noise that were causing the tachometer problems. Basically it cleaned up the voltage signal. Whatever the reason, it worked. I even confirmed it later when the wire broke off of the condenser and the tach quit working. That was with a GM HEI module though.

It did work when the engine was cranking, but stopped when the engine started. Might be a clue for the guys that know electronics. While cranking the overall system voltage will be lower. As soon as it starts you get alternator voltage. Do you have any spare E12-80 modules? Maybe the problem is there. Might be worth a swap, just to confirm. At low RPM the module will be "working harder" to limit current for "dwell control". I don't really understand the details of current-limiting but that's how the ZX and GM HEI modules work to get maximum coil charge without overheating the circuitry. And, of course, don't overlook the grounds. The module grounds through the distributor body and the distributor body grounds through a separate wire or the mounting pedestal.

The conversion parts and engine might make it worth the money. Even a Chevy manual transmission adds value. Who knows what diff the guy used. Too bad there's not more detail. https://jagsthatrun.com/collections/datsun-zx

You should check for power at the switch first. The odds of a new switch failing are slim.

Did you mean switch, not module? Can't remember the details of the first problem that caused you to replace the part, whatever it is. Maybe write a short history of problems up to now. There's not much to the system that sends power to the starter solenoid.

SU's use a piston to control air flow. Might be that your pistons are stuck, among other possibilities. Not sure how to fix that.

Is there a typo? Why would a shorted O2 sensor affect a cam sensor? And why would anything "burn up"? No fuses? Just wondering.

Might be the ignition switch. Fairly common for the pins in the switch to get loose and lose connection. Or for the mechanicals to wear and the key does not turn the electrical portion of the switch far enough. If you can get to the switch and take it apart you can get the definitive answer. Turn the electrical portion with a screwdriver and see if you get power then.

The Z switch is just a two wire switch. Power on one side and ground on the other. I converted mine in to a "headlights still on" warning buzzer.

Your battery is probably low on charge.

The switch above the brake pedal is known to break. Two wires and a spring loaded button. https://zcardepot.com/products/brake-light-switch?_pos=1&_sid=e77632f40&_ss=r