Zed Head

Spark plugs on the Z engines are about the easiest you'll find anywhere to remove and inspect. If they're dry you'll know more, if they're wet you'll know more. Why wait?

p.s. if I recall right it's a 74 260Z with carbs. So many electrical problems it's hard to keep track... Pull a spark plug and check for wetness. With carbs, when you smell fuel it usually means that flooding/fouling has occurred. Might be because you didn't have spark, maybe. But even if you solve the spark problem, if it exists, flooding will still stop it from starting.

Some coils have instructions to mount them straight up, not sideways. Maybe there's a reason. It would be interesting to see if there are any ID marks on it. https://www.cpperformance.com/instructions/120-8202.pdf

The Engine Electrical chapter shows all of the pins that you can check at the plug for a short to ground. If it was me I'd just unplug that plug, set my meter to beep for continuity and poke, poke, poke. The beep will be the problem circuit. Edit - actually, the beep would not be the best signal. You'll get a beep through the relay solenoid. Best to read resistance. The one close to zero is the problem. Then find that pin in the wiring diagram and follow it out. Here's another circuit, after the relay. If you find that the ignition relay itself is good then check each pin after the ignition relay. The relay will pass plenty of current to blow those fuses.

Here's a picture of my old ignition relay, from a 76.

Don't go bigger on the fuses. There's nothing on the Z's that will pull 40 amps through one circuit, I think. You must have a short circuit after the ignition switch. Could be the ignition/accessory relay or something after it like the ignition system (coil, etc.). If your car was or is an automatic there are two inhibitor devices that could be shorting. The simplest starting point is at the plug to the ignition switch. Unplug it and check the black with white stripe for continuity to ground and the same for the black with yellow stripe. That will split the system in to two parts. You have a dead short after the switch. SteveJ just posted. Better see what he said...looks rational (of course). So, there's two separate things that you can do to narrow things down.

Might be that the engine was hotwired, or the PO tried to hotwire it and did it wrong. Might be that the PO replaced fusible links with full gauge wire. Lots of "might be's". If you had a coil blow up just by connecting the battery, that's a sign of major wrongness. Better get a meter and start using it. You really really don't want to smoke the wiring in the harness. You can test everything you need to test without connecting most of it. You don't need a coil yet. You don't even have enough information to choose a correct one. Also, Nissan did not use the standard red for positive, black for negative on their battery cables. Make sure you know which is which. The colors won't tell you anything. Good luck.

Was the engine running, or the key on? I'd guess the P.O. connected the blue coil negative wire to a ground terminal or shorted it out by accident, you turned the key on, the coil overheated and popped it's top. Is that a Blaster or did the PO just paint the stock coil red? Download the 1980 EFI book, and the Factory Service Manual if you want to figure things out quickly. Replace and hope doesn't do well on the EFI cars. No offense intended. If the PO bypassed the ballast resistor then he/she probably did something with the ignition module. Might even have a ZX distributor on there.

Looks like you can still find NOS stuff out there. I'd pick a few links but the Google page has too much good stuff to choose just a few. https://www.google.com/search?q=heathkit+cp-1060&rlz=1C1SQJL_enUS862US862&oq=heathkit+cp-1060&aqs=chrome..69i57.13132j0j15&sourceid=chrome&ie=UTF-8

Maybe you're thinking of this saying...

Do you have a picture of the exploded coil? I've never seen one or heard of it happening. An internal short could pass enough current through to heat it up rapidly but even then the negative terminal wire and positive terminal wire would have to pass the current, and the negative terminal would have to supply a ground path. If the ignition module was shorted or the negative post wire shorted to ground, the coil could heat up more slowly and maybe get hot enough to smoke or something. Either way, the coil itself would only be the cause of the "explosion" if it was internally shorted, and there was a path to ground on the negative post side.. More likely that the source of the failure is somewhere else. Better check the other components before you get carried away with new parts. Heat comes from current and current only happens when the circuit to and from the battery is complete.

Sorry for stirring things up folks. I got carried away with what seemed funny about the first post. "Spend $14,000...you're welcome." Funny.

What year Z and is the ignition system the factory stock parts or has it been modified? Primary resistance is your main concern. Welcome. Most people don't get exploding parts to help them diagnose a problem.

Edited/ The video was pretty funny, I thought, but doesn't help anything.

Edit - I should not have replied to the post. Should have let it fade away. Sorry. (Removed some stuff here). I only posted the graphic to show the physical distance. I did a Google on the name and zip code (weird that zip codes are global).

Edit - I wrote the below while you posted. Another simple check of just the lines and system up to the calipers would be to disconnect both calipers and place the ends of the lines in two containers. Sit in the drivers seat and pump the pedal a few times (don't bang the MC piston off the end of the bore, use short strokes). If the lines are open and pressure is fairly balanced you should get about equal volumes in each container. If you don't then you can just go backward toward the MC. Disconnect at the switch and make some stubby lines to check flow there (you have a number of old pieces laying around by now). Do the same test. Since there's only a single line for the fronts to the switch there's no reason to go above the switch. There's no left-right up there. That will break the system up in to three parts - the calipers, the lines, and the switch.

Don't they use the same calendar in Neuvecelle as the rest of the world? This thread is 13 years old. mikewags hasn't visited the site since 2010. Welcome to the forum.

Maybe this will help, below. I see flow and pressure and force being used all in the same train of thought. Flow is what starts things happening, but once flow stops you're left with pressure. And pressure is what creates the force on the rotor that stops rotation, via friction from the pad on the face of the piston. If you know that you have flow when you press the brake pedal, when the brake pedal stops moving you can stop thinking about flow and focus on pressure. Once flow stops you have to have equal pressure throughout the system. It's a law. https://en.wikipedia.org/wiki/Pascal's_law

I'm not saying that blocking the holes is your problem. I'm just focused on your testing methods. You haven't isolated the source of the problem to a smaller area. Everything after, and including, the switch is still in play.

I'm just saying try the same things on both sides. You have one side that works and one side that doesn't. See if you can blow air through the inlet to the bleed screw on the right like you tried to do on the left. And yes, I am saying that the piston might be able to press far enough in to block the holes. The calipers are designed for a known thickness of pad and rotor. So, whatever works on the right, match it exactly on the left. And, vice-versa.

You didn't describe the same action on the right side. Since you have a symmetric system you're in a good place to compare one side to the other. Might be that the piston will retract in to the bore far enough to block passage from the inlet to the bleed screw. With two sides that should be equal you can compare identical actions until you find the one that's different.

Hydraulic principles say that if the system is connected correctly that you will get equal pressure on left and right. It's not possible to have one side pressurized and the other not. So, air leaks are not an option if the right side works correctly. If you are getting fluid from both sides by pressing the pedal then what might be happening is that the piston is bound up in the caliper. There's pressure but no movement. Assuming that the hydraulic lines are correctly installed. Or, there's a blockage inside the switch. You might disconnect both lines at the switch and see if you get good flow from each port. I sure hope that I don't start seeing a bunch of pharma ads about flow or stream... p.s. I wrote this while others were posting. But, "first principles" apply here, as far as problem solving. The end of the warning switch has an inlet and two outlets, and hydraulics apply. The only other variable might be time, but if somebody is sitting in the driver's seat with their foot on the pedal the fluid pressure will equilibrate.

Blow some air through them.

Left and right use the same chamber in the warning switch. The pressure should equalize between left and right. Hydraulics.

With the newer slave cylinder that is what is supposed to happen. The internal spring pushes the slave piston forward, taking up the play. Self-adjustment. Can you push the rod back in to the slave cylinder with everything connected and ready to use? If you can't then you might have a problem.