Zed Head

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.

A thermostat that's stuck open will behave this way. Coolant flow isn't controlled so overcooling happens at freeway speeds. But it wouldn't cause temperature to go high. Not enough air flow would though. So a stuck open thermostat and poor air flow kind of fits the symptoms. The thermostat STOPS flow it doesn't cause it. The thermostat is there to increase engine temperature. People get that backward often. So the signs actually show that the thermostat might not be working properly. If the head gasket is bad it will typically overpressurize the system, from leaking exhaust gases, causing fluid loss. If it's an air flow issue, opening the hood typically has an effect. Here's something that I don't think was mentioned - is your heater core bypassed? That can cause overheating by lowering the coolant flow through the block and head.

There was a guy a few years ago who put a P90 on dished pistons just so that he could sell the car. We told him about the CR but he did it anyway. Still wondering who ended up with that car.

2-4-6 Blue brings up a good point about the head gasket and the timing. Could be that you really have a blown head gasket causing your problems.

I'd go with a shroud also. If the car is lowered and/or has an air dam in front the fan might not be pulling air through the radiator, just spinning it around behind it. Nissan built those shrouds for cars with AC because the fans can only move so much air without them. You might also go back to a stock radiator. Your engine is mild and doesn't really need what you have. I have an OReilly cheapo radiator and a shroud and I have zero cooling problems even on the hottest days. By the way, N47 is a stock 77-78 280Z head, not ZX Turbo. You have a plain old 77-78 NA engine at this point. Should be easy to cool.

It's not really a "pig tail", it's a length of wire that comes from the connector by the fuse box. It could either run down the door under the carpet and across to the switch, or across the dash and through the console to the switch. But it will be just a wire in a bundle of other wires. C-6 is in the junction block by the fuse panel. Here's a link to the factory FSM. Body Electrical chapter, Meters and Gauges has the diagrams. http://www.classiczcars.com/files/category/13-280z/

Yes, it does. Is there a problem? Not really clear why there's a question, no offense. Edit - looks like there's a fuse...

I changed my vote. Much depends on how fast the meter reacts, and how well damped the needle is, among other things. I overlooked the basic "changed something and it got better" description. That's the major clue, I think.