Zed Head

Looks like they are not color coded. So, your best bet is to unplug them all and confirm continuity for each power wire to each injector. Then check the wires in the dropping resistor itself if you find that all injectors have continuity. You'll have to remove the resistors for that. The problem would be either in the dropping resistor assembly itself or in the harness on the way to the injector plug. Edit - just noticed that #1 should come from the resistor with five wires. Just keep narrowing things down... If the drawing is correct you can even tell which pin is #1 by its position.

I would unplug the dropping resistors (you might be able to do it without removing the resistor, can't remember), then check continuity to the injector #1 plug from the resistor plug. I don't know if the wires at the dropping resistor are color coded or not.

You're making good progress. You probably have a bad connection somewhere in the wiring harness. The most likely spot is at the dropping resistors, which are underneath and behind the washer fluid jug. Some screws hold them in. I would go there and take a look. That's where the power passes. You can check voltage in to the resistors at the plug too. Several injectors are fed through each resistor, so check each wire carefully. Edit, actually voltage in to the resistor would affect several injectors. Focus on voltage out.

Cliff's method works. Another is the bolt pattern. Nissan did not drill theirs for both. 225 is 6 evenly spaced bolt holes, 240 is 3 sets of 3. 225 240

Hey! 39 / 11 = 3.54. That's what all of the 280Z R200's are. I went through the whole thing of trying to take out only the parts I was working on when I first did my diff, prying and torqueing bits and pieces. It was a pain. If I recall correctly, I ended up later just removing the mustache bar end nuts and the front crossmember and dropping all three pieces down as an assembly. The mustache bar makes a good handle for balancing and you can just drop everything straight down. It works for assembly too.

It does look more like injector alone. You can do a lot before swapping injectors. You can measure resistance across the pins. Should be about 2.5 ohms. You can connect a 9 volt battery across the terminals, with a fuel pressure gauge connected. You should hear it click and see pressure drop as the fuel is squirted in to the cylinder. You can put a noid light in the injector plug and see if it flashes while the engine is running. If you had a bad vacuum leak at the injector you might also get a lean misfire. You could check that by squirting starting fluid or carb cleaner at the injector gasket while the engine is running. Should get some fire then if there's a leak. That might explain why you're hearing the right noises and seeing sparks but not getting fire.

I noticed on my engines that #1 seems to run lean, the plugs are always whiter than the others. I think it has to do with air flow, #1 must get more air. So if your system is tuned to the edge of lean, #1 might be too lean to fire at idle. Just a guess. You could adjust the idle air screw to richen things up. Screwing it in will divert more air past the vane, adding fuel. You could also pop the black cover and move the counterweight. The dead cylinder might be only happening at idle. That might explain why the plug porcelain is dark, indicating combustion at some time. A dead cylinder with a new plug should be "like-new" white.

The 1971 240SX. Kind of early for it... https://en.wikipedia.org/wiki/Nissan_240SX Those cars are pretty far out there. Probably nice and dry. https://goo.gl/maps/FY845t1sCBXpqpXT7

There is a pretty rare vehicle in that collection.

I think that it already has a draw-through turbo. Don't know much about it but I found an old thread showing a similar setup on an L4. Edit - it's in @Racer X 's neighborhood. He probably knows about those old turbo kits too. https://ratsun.net/topic/57895-datsun-510-l20-looking-for-turbo-kit-for-it/

Here's a post from the middle of the last conversation. It's a hybrid 240/280. I never did find out what the firewall VIN was. I just noticed that it even has the 280Z air filter and ductwork (edit - actually I did notice that before...). And the charcoal canister.

The 1972 280Z (we had much discussion about this one in the past. Can't remember what we decided) is still up on the Beverly Hills site. Looks like new pictures. Like they're daring somebody to buy it. https://www.beverlyhillscarclub.com/1972-datsun-240z-c-11820.htm

The purple filter cover is a nice touch.

I Reported the new member's post. That should do it.

Might be the owner's Supra.

Google Maps has a feature that lets you look back at their previous images. Wonder how far back it might go.

Another one. Same video.

Not a movie or TV but a car show video. Couple of Z's. Might have posted it before.

Are you using the word "ground" correctly? Or understanding how the ignition system works? No offense. It sounds like you're saying that the ECU is not picking up the distributor trigger. Is it the factory variable reluctance (VR) trigger? What is under the distributor cap? Stock parts or aftermarket parts? A picture would be good. The VR trigger does not use a ground it uses two wires that transmit an alternating current wave form. It's not uncommon to have triggering problems with the aftermarket engine management systems or ignition systems, like MSD's. Some trigger systems are set up for Hall effect triggers as an option. People get them mixed up sometimes. Might be worthwhile to show your wiring scheme. The distributor ground might not be important in your case, although I think that it migth serve the purpose of dissipating static charge or stray spark plug wire spark. It's definitely important with a points system.

You could even draw on SteveJ's picture. Do something. There's a lot of different mushroom shapes out there. Might be that the diaphragm has blown and since there's no fuel passing through the pump it lets oil leak out. When fuel is flowing sometimes they leak fuel in to the crankcase.

It shouldn't really matter. Unless you screwed and unscrewed the nuts a few time while you were working on it and the studs backed out. Might be that you didn't have full thread engagement, or maybe the block threads are damaged. Since you have the head off it's probably a good time to really look at how well the studs engage the head. Just more thoughts. The ARP system is smart but the old school head bolts seem to work well on the Datsun engines. Good luck.

Just offering a different view. ARP's instructions are not the clearest but it looks like they want 60 ft-lbs if you use their lubricant. Did you use their stuff? https://tech.arp-bolts.com/instructions/202-4202.pdf

Does your theory fit? The nuts are still torqued on to the studs, pulling up on the threads, providing clamping force. Doesn't really matter if the studs aren't seated all the way to the bottom of the hole. Has the head been resurfaced? Is the deck flat? Seems more likely that the problem has a different source.

The video had some tips and tricks. Obviously, you are well past this step. Don't forget to use good break-in oil on the first engine start. The cam lobes are sensitive.

The OP is in Austin. I've read about the N42 heads over there. They were still running carburetors right?