Zed Head

What does the tachometer needle do when it's "losing fire" or runs unequal? It's a spark counter. Can't remember your car. Are you running carbs or EFI? Have you tuned it up recently? Spark plugs get dirty and gap increases as the electrodes wear.

If you can measure power and you can confirm ground then you should get light. You forgot to describe the year of car - 1977. B is on a switch that's right there at the light. It's push-on, push-off switch. BR runs through the door switches, which are only closed when the door is open. But they do get stuck. Mine were and needed some contact cleaner and working back and forth to get right. You might just hook your meter up to B and/or BR and work the switches to make sure the ground is good. That's all that they do, supply the ground. If you have power to the terminal at the bulb that's connected to blue/white then the problem has to be the grounding. I copied the page from what I think might be the 1976 FSM, not really sure. I know I sent you to Mike's copy but I'm not really sure what year that is and don't want to run the application that's required to unzip it. I got mine from nicoclub.com Anyway, here it is. It's probably the same. It matches your wire colors too, but it's on a different page.

What brand and model of coil did you get? We can tell you if it's right.

There are people that will act as transaction agents for things like this, for a fee. There are a few threads on this site from people who didn't get what they thought they were getting. Even the shipping companies can make mistakes.

Beermanpete had the best suggestion then, in Post #3. Just make sure that the coil specs match. That's probably not the problem with your tach though. But good luck.

Pretty sure he got it running. He used "turn" when he meant "fire" or "start". theab, locate the source of the leak first. Can't really decide what to do if you don't know where it's leaking. Check the bottom of the radiator, the hose to the heater core, the back of the cylinder head, etc.

Loose S. If it's in the harness it will still be there with the new/reman alternator. Loose L might do it also. No winding current means no charging. The loose parts could be inside the alternator. Guess you'll find out. Those studs in to, through, the case can come loose. When you remove it, shake it hard and see if anything rattles.

Starting fluid is always a quick way to see if most of the basics are in place. Any chance you could add more information? For all we know you either just pulled it from the bottom of a lake, or it was running fine ten minutes ago, or anywhere in between.

I get it. Gelis much? UR? Too bad... Nice to not read much about that guy these days.

Edit 2 - I screwed up. You can get the Start resistor bypass by connecting black/blue to the same terminal as white/black. Black/blue is Start power, black/white is Run power, and white black is just the line from resistor coil positive, to supply coil power. Looks like Nissan used half a ballast resistance for Start power. Deleted, realized I didn't understand what the OP was describing. Edit - found it, attached. Black/blue and black/white would connect together to one end, and white/black connects to the other. But you'll lose the Start bypass which will drop coil current during starting. 1974 is the first Z with electronic ignition but they still used a ballast. The condenser is to save the points, the ballast is to control current through the system. They're pretty interesting, the resistance changes as they heat up, due to current, to drop current. Self-actuating. But the other issues of which coil and which ignition system and which resistor you should use can't really be answered. You could measure resistance of the two and decide if there's any benefit to the new one. The Starter bypass might be helpful, although they got rid of it in the later years with more powerful ignition modules. Why'd you get a new coil anyway?

I'm still using an old 1981 Nissan alternator that I got from a junkyard engine I bought. Probably 40,000 miles on it. I have a new Autolite replacement from OReilly in the box on the shelf that I'll probably never use. It's the lifetime warranty replacement for the first OReilly alt that crapped out soon after I installed it. I'd go get a junk yard Nissan alternator myself. Just make sure it's Nissan.

Are you looking at cross-references too? The early 80's Maxima alternators will work too. Bad S same symptoms...

I feel bad for bashing on the Seafoam. Seems like you were looking at Seafoam to fix what's really just a tuning problem, and maybe some other issues. The engine almost never gets up to temp? Maybe you need a new thermostat. There's another thread going on where thermostats were mentioned. I noticed a significant effect of replacing what appeared to be a good thermostat with a new Nissan thermostat. The old thermostat seemed to open at the correct temperature, tested on the stove in a pan of water using a thermometer, but I think that it had a weak spring and was blowing open in operation. The engine ran cool and would fluctuate from below halfway to halfway. With the new T-stat the needle just slowly rises to a little over halfway and sits there. Doesn't budge once it gets there. Very noticeable difference from the old one.

Is that the lawnmower stuff? I didn't search the youtube tube.

No offense, if you're a Seafoam fan. There just doesn't seem to be much evidence behind it. You'd think that they'd have a video that actually showed a dirty engine getting cleaner inside. They do have one though - https://seafoamsales.com/sea-foam-official-video-how-to-clean-a-fuel-injection-gasoline-intake-with-sea-foam-spray/ "backwash" vapors at 2:25.

I think that they must add some butane or pentane so that intake vacuum will cause it to foam. So it probably does foam up and get the solvent in to areas it might not otherwise reach. But it won't dissolve the typical hard carbon deposits in an intake runner or back of a valve, I think. Somebody wrote about that somewhere out on the internet. You just end up with clean carbon deposits.

That's the image they've created. But run the stuff through a freshly rebuilt engine you'll probably get just as much smoke. Check the SDS - http://seafoamsales.com/wp-content/uploads/2017/01/Sea-Foam-Motor-Treatment-SDS-v20161205-ENG.pdf "Hydrocarbons" come from oil, anything/everything from methane to diesel could be in there. But they're all just crude oil fractions. A bottle of rubbing alcohol and a gallon of paint thinner and you might have the same blend. http://www.gcelectronics.com/order/msds/226.pdf

If you can, stick your meter probes through the back of the T plug, or pull the T plug partially off, and measure voltage at the S pin (can't remember if it's the vertical or the horizontal of the T). Dave's adapter works on the assumption that the wires from the external VR are correct. Sounds like you're missing the S connection. S should connect to the battery positive circuit. If you don't know which is S, measure both with the key at Run. They should both show battery voltage then.

Here's a good one.

The narrower range would be a sign of a belt slipping less. The thing about the ammeter is that it shows whether the battery or the alternator is supplying the current so can have a large swing as it goes negative or positive. A voltmeter will always sit around 12.6 and the same current direction change will only cause a fraction of a volt movement on the meter. Plus any "wild" movement of a gauge is a sign that the needle damping mechanism is damaged. You can buy spray-on belt dressing for a few dollars. But any squeaking of the belt is bad. Once they start slipping the surface overheats and the rubber hardens. Then they slip more.

Some of the prices seem reasonable. $45 for an ammeter'fuel gauge, not bad if it works. Fun to browse through and look for interesting errors.

No problem, I learned something about my own parking brake. A good puzzle. Check that Body Electrical chapter for the dome light circuit. Pretty sure I flipped by it on the way to the parking brake light page. I think that it might be similar to the e-brake with several possible ground circuits. You can push the door button with your finger though, easy check. Start a new thread for LED's. There are some guys here who know quite a bit about them. I don't know much.

That's the way to do it. But keep your eyes open for a cheap ECU. Most of us out here have a spare or two because the old electronics generally seem to be drying out and dying. Ignition modules and ECU's. I had a bad ECU myself and it was supposed to be a spare. A few others have had bad ECU's over the years. And they tend to flood out as part of the dying process.

That sounds right, except for the rapid leak-down after shutoff, which is really just an inconvenience. The numbers, 37 and 35 and 30, for the conditions you described, all look about right.

I think that you might be right. I just went and looked at my 76 and I can see the GY wire coming from what looks like under the passenger seat and connecting to a black wire via a bullet connector. The way to test the black wire would be with a meter or a continuity checker. You'll get continuity to ground when the lever is up, and the circuit will open when the lever is down. That would show that it's a path to ground controlled by the lever position,which is how the system functions.