FastWoman

Hope that helps!

Finally, "disconnected white wire from/through firewall" Here: This wire isn't OEM. It was added by one of the previous owners, and I would have no idea what it is. You should be able to find it on the other side of the firewall and see where it runs. In all likelihood, you can take a pair of wire clippers and remove as much of the wire as you are able. I suspect it serves no more purpose. I see the end wrapped in electrical tape, so it might be live (+12 V). Be careful when you snip it that you don't short it to ground. Perhaps tape the exposed end when you're done, just to be safe. The two black wires emerging from the same hole are also non-OEM.

Next, "black wire disconnected, other end attached to outside of compressor. Maybe ground?" Here: I assume you mean the black wire on the right. If one end is attached to the body of the compressor, then it's indeed a ground. Black would be the correct color code for ground also -- although black is also used for other things, like almost every wire in the EFI wiring harness! Anyway, this black wire, which is a ground, should probably be connected to the body ground point on the left side of the photo.

Next, "from red (sensor???), connected wire. near coil" Here: The red "sensor" is a noise suppression capacitor with some red paint on it. Neither end is connected. I don't see it diagrammed in the ignition circuit, and you can probably remove the part. It was probably installed to suppress electrical noise to a previous owner's stereo system. By the way, there's a clip that holds the coil wire (that goes to the distributor). It wants to be inserted onto the metal tab about an inch to the left of it. You also have the wiring harness (wrapped in black electrical tape) running very close to the coil wire. That's probably not a good idea. It would be good to have a bit more distance between them.

In response to Redwing's private email, I'm starting this thread for her. She has 5 disconnected wires and is trying to figure out what they do, where they're supposed to go, etc. First are "2 blue wires coming out of wrapped bundle" here: The one on the left (from center of image to top center) is not blue. Rather, it appears to be black with a blue tracer (stripe) on it. (Very big difference!) That may be the wire that goes from the "start" position of the starter switch to the middle of the drop resistor for the ignition coil. This isn't absolutely necessary for your engine to run, but it energizes the coil a bit more when you're cranking the engine, making it start more easily. I have no idea about the wire on the right.

What Patcon said! So you say there was spark, but the engine wouldn't run longer than 5 sec? That sounds like a fuel issue to me. You should try the starter fluid test next time. If the engine runs for a few sec on the starter fluid and then dies, that confirms the ignition is working and your fuel is not. Probably the best place to shoot in some starter fluid is the connection from the back of the intake manifold to the brake booster line. Disconnect the black hose that's about as big around as your finger. Shoot a good blast of starter fluid into the intake manifold (maybe a 1 second shot). Put the hose back. (You don't need to tighten the clamp yet.) And then without piddling around too long, crank the engine. After you're done, don't forget to re-tighten the clamp on the brake booster line. I sure would like to see a better photo of your engine. The one you have is sort of small and fuzzy. I'm seeing a few odd things that I can't quite decipher. There's what appears to be an AC hose coming out below your throttle linkage and going to a dryer/accumulator on the driver side fender? Nothing wrong with that, but different. Then I see what appears to be two red, silicone rubber hoses feeding coolant to the block beneath the auxiliary air regulator (AAR). I question whether that can hold pressure correctly, not being reinforced. Then there's a vacuum line that seems to dive between your #5 and #6 intake runners -- probably not a good idea. And then your fuel inejction rail seems to be turned at an odd angle. Other things too. It would be good to have a better look. I'll have a look at your wiring photos too. Give me a little while to study them...

Personally I'd drain the tank. The gas will be no good 3 years from now -- a waste of perfectly good fuel/money. Drain it, and burn it in your other vehicles. You shouldn't get condensation in the tank if it's in your garage. Even better, I do like the idea of starting the engine every couple of months. But you want to have non-ethanol gasoline in your tank, AND you want to keep your tank fairly empty. Every couple of months, pour in another half gallon or so of gasoline, and run the engine until it's warm. Keep the battery on a trickle charger. Your tires might be questionable after the long hibernation anyway. It's said you should replace your tires every 3-5 years regardless of wear, because of dry rot. I doubt most of us actually do that with our Z cars, because they don't get a lot of miles. However, it might be sensible just to leave the tires on the ground, suffer the flat spots, and take the car for a drive up and down the driveway every couple of months, just to get the fluids moving. Don't forget to run the AC if you have it!

No idea about the whoosh. I suggested a way of examining the issue from the hose that connects to your carbon canister -- somewhere in another thread. I'd try that. It could be that your vent is blocked (e.g. rusted closed) or incorrectly connected. I suspect (and could easily be wrong) that the fault doesn't lie with the check valve. Check valves usually go bad by failing to check, not by blocking off flow. Perhaps you can give us some wire colors on those wires. If they're black, they might have tiny little numbers printed in them every several inches. You might have to clean them to see the numbers. And if you're like me, you'll have to read them with your reading glasses. Oh, if you have your car up on ramps, you might be able to have a look at the fuel tank vent line. It runs from a fuel air separator to the side of the hatch area on the passenger side (which you won't be able to see), down into the space in front of the fuel tank, to that check valve (as I recall) and then to a metal line that should run to the engine compartment, then to a rubber hose that should lead to the carbon canister. It would be interesting to know if you can pass air through the metal vent line. (It should move freely.)

Hey Jai, I'm glad you're still with us! Hang in there, and you'll eventually learn the motor. Reading and re-reading the beginning of the EF section is the very quickest way to learn. Good material! Glad you have your battery posts cleaned up -- making progress. The dead tachometer is an interesting observation. This wouldn't be from a wire that's not hooked up at the coil or distributor. The engine does run, usually, and for this to happen, the ECU (engine control module -- the "computer") has to get an ignition signal. This is done with the exact same wire that feeds the tachometer -- a wire that branches somewhere under the dash, as I recall. One possible reason for your tach not working is that the connection is dropped somewhere, but it wouldn't be at the coil. Perhaps under the dash? Another possible reason might be that the ignition is weak. I've not heard of a weak ignition not triggering the tach, but you never know. It would be interesting to know how long a spark your ignition can create. If you can create a pretty long spark, and if your engine does run, the tach should also have all the signal it needs (assuming it is hooked up). Can you photograph the wires that are hanging for us?

Very nice! Congratulations!

Shouldn't be any tach or speedo issues. Tach gets input from the coil. Speedo gives output to the BCDD, which operates independently of the EFI.

Wow, that was a LONG time ago. I've gone pretty far down the road since then, and I can't really remember where in the road that was. But yes, I've resolved that problem. My engine runs pretty well now, but it does miss a bit on hard acceleration. The ECU is probably at fault for that. Old age is not kind to linear circuitry. I'm hoping "Superlen" will soon come charging over the hill with a drop-in replacement digital ECU for our cars. I did confuse my engine's very LEAN running for a rich condition. Either results in black soot. A lean condition also results in backfiring out the intake, the exhaust blowing hard and spitting droplets of water, and the exhaust manifold geting quite hot. My engine ran lean because of massive vacuum leaks and drift of the ECU. I remedied the latter problem by adding resistance to the coolant temp sensor circuit. Restart problems after sitting were due to leaky injectors and a bad fuel pump check valve. Now with new injectors and check valve, my system holds pressure virtually indefinitely. All the details are in past threads. One in particular is "purs like a kitten." You'll find most of my major finds and remedies detailed in that thread.

Jai, I think that fan will mount up to any 280Z motor. There might be some interference with the oil pressure sender. You'll also need to cobble up a thermostat to control it. I don't know how that was done in the ZX. I suspect you'd use a cheap bimetal switch to actuate a relay that would switch power to the fan. But it won't be completely plug-n-play. You can see the fan and its cooling ducts wrapping over the valve cover in this photo: https://www.bing.com/images/search?q=280zx+engine&view=detailv2&&&id=B70D7D444A06F07E5F1DA629E44CEA88EC4E8C74&selectedIndex=9&ccid=ZzOC9W8y&simid=608016328603668167&thid=JN.Erq1JsMe4q6j1zR7rC2qBg&ajaxhist=0

Cool! I'm certain that was at least 90% of your problem, if not 100%.

I would think it would work, perhaps with some minor mods (but probably no mods needed). I think the fuel pump shutoff is a non-issue, because that's handled outside the EFI system on '78 (and I think '77). In '78, the fuel pump will run with signal either from the alternator or the oil pressure sender or both. The EFI doesn't matter in that scenario. I think there are also differences in the EGR, but again, that's not handled by the EFI. The '75 system might be an upgrade because of the Bosch (vs. Hitachi) ECU, which doesn't seem to have the same leaning-out issues with age. The '75 AFM would be a downgrade if original, because it doesn't have the backfire relief valve. Backfires can actually bend the AFM vane. But overall, I'd say to go for it. You can deal with a '75 EFI one way or another.

Redwing, I think you could test your vent system (including the check valve) by doing the following: 1. Disconnect the fuel vent line from the charcoal canister. It's the line that doesn't lead to the engine. Instead, it leads to one of the metal tubes running from near the firewall to beneath the car. 2. Open your gas cap. 3. Wipe off the hose, and blow air (with your mouth) into it. That's the air returning to the tank. You should feel some resistance, but should be able to blow in that direction. If so, the vent line is clear, and the check valve is letting air flow in at least one direction. 4. Next, put the cap back on the tank, and blow more air into it. You should feel resistance building as you pressurize the tank with your breath. If that happens, good. Now go and crack the gas cap, and there should be a bit of a whoosh. If so, all good. 5. Hopefully by now most of the gas fumes have left the vent tube, and you can try sucking air the other way. This may be more difficult, but the air should vent in the return direction. Be careful of the gas fumes, though! You don't need to suck much air out, just enough to verify that the check valve will pass air both ways. If that works, then you're probably good. If not... 6. Look for the check valve underneath the car. It's a small, cheap looking black plastic part. Remove it, and try blowing through it in both directions. One direction should flow pretty easily, and the other less easily. If it is good, then reinstall. It should be oriented to let air into the tank more easily than out of the tank. As I said before, there's too much about the fuel injection to explain to each and every person who comes along. Nissan's factory service manual really is the very best resource you can study to learn this system. I really mean that. It's available for anyone to download absolutely free, with no obligations or strings attached, courtesy of the Datsun Z community. The one for the 1976 280Z is here: http://xenonzcar.com/s30/files/FSM/76_datsun_280z.zip This is a zipped file, so you will have to unzip it. Please let us know if you don't know how to do that. An alternative is to buy a used manual online. Here's one for $70 -- absolutely the best $70 you will spend on this car: http://www.ebay.com/itm/1976-Datsun-280Z-Service-Manual-Shop-Repair-WORKSHOP-FACTORY-ORIGINAL-/151608238831?hash=item234c8e22ef&vxp=mtr The introduction of the "EF" or "Engine Fuel" chapter even explains how fuel injection works. It was written for people with nothing more than a knowledge of carbureted cars, back when fuel injection was a new thing. There is very little we can do to help you if you don't equip yourself with some very basic knowledge of the fuel injection system. Speaking the same language is essential in this process.

Yeah... I know... I've heard worse: A friend went to look at a Jeep in beautiful condition from the ad -- PERFECT! When he first sees it, it's a thing of beauty. Then he walks to the other side and sees the whole side is scraped up and dented in -- a nasty side swipe! He exclaims to the owner that the ad said the Jeep was perfect. The owner says, "Yeah, but if I had told you about the body damage, you wouldn't have come out to look at the car. I mean, it still runs great!"

Zed, if we're talking about the same part, mine is a little plastic doodad, about the diameter of a quarter if I recall correctly, mounted to the bottom of the car in roughly the same vicinity as the fuel pump, just prior to the hard lines. Redwing, pressure in the tank is normal. The whoosh is normal. Too much pressure and whoosh is not. If the check valve is functioning properly, there will usually be some pressure in the tank.

Wow, Jai, you're really digging through a lot of old posts! Thanks for the offer of help! I was simply looking (back then) at a couple of 280ZX's and was hoping another Z nut could preview them for me or help me to look them over. It turns out both "rust free" cars had some pretty bad rust. Steve, I had been in touch with Patcon, who was going to meet me to look at one of the cars. (Nice guy!) However, when I saw the rust, I texted him to tell him not to bother. It was a heck of a long drive to find out that both owners had lied in answer to a very specific and important question. With that negative experience, I decided not to make any more long drives to look at what appears to be a promising vehicle. But thanks for the response and offer of help!

Er... a bit of clarification... Leave the fuel lines alone for now. I'm simply talking about all the vacuum tubes/hoses. Also, when you replace anything, whether it's a tubing or wire, do it one tube/hose/wire at a time, so that everything stays hooked up the same. This assumes everything is hooked up correctly, which it might not be. But you can find that sort of information in the downloadable factory service manual.

Enjoy the ride!

Pretty car! FAIW, it's got a '77/'78 bumper and molding on the front -- probably wrecked at some point. Then again, with cars these old, it would be unusual to find one that has never been wrecked. The engine bay photo is pretty fuzzy, but there does seem to be an assortment of hose types, suggesting that replacements were only done when a leak or break was discovered. I'd recommend replacing all of that junk with new. It should cost all of $15. The wiring repairs are also pretty amateurish. There are probably some good youtube videos on making wire junctions -- small learning curve + a minimum of equipment -- not rocket science. My usual approach is to crimp, fill with solder, and then insulate/seal with marine-grade heat-shrink tubing (which you can buy at Harbor Freight). I'd remove all the nasty looking splice work and replace with new lengths of wire. And depending on the condition of the electrical connectors, I'd replace those with new ones from ebay (search for "280Z injector connectors"). The 2-wire ones are readily available. The 3-wire (throttle position sensor) is available from more modern vehicles in the wrecking yard (e.g. Volvos). The large airflow meter connector is probably fine, and you would have a hard time finding a good replacement anyway. And you should take a look at your fusible links (under clear plastic covers on the passenger inner fender). They might be crusty and unreliable. The covers are often gone, exposing the contents to moisture/corrosion. You should pull off the battery cables, clean up the posts and connectors, clean the top of the battery, install felts, grease the cable clamps, and reinstall. Heck, you could probably use new cables, judging from the corrosion. All of this is detail work that you can do with a minimum of tools, knowledge, or strength. You'll probably eliminate a few problems in the process, without even knowing you did it.

Well, black isn't good, but it's much better than milk chocolate! When you have your oil changed, make sure the old oil doesn't just drain into a big waste barrel, like they do it at one of those Jiffy Lube sorts of places. You want to have a look at it before it gets dumped. (Completely irrelevant to the conversation, but... Back in the day of the "superslick motor oil" craze, I was in love with a motor oil called Arco Graphite, which had micronized graphite suspended in the oil. It was black as ink. You should have seen the expressions of everyone who saw it! They thought I had never changed my oil!)

Jai, it's not safe to assume your engine is running rich, just from the black exhaust. It could also be running very lean. (This is a common misunderstanding, even by professional mechanics.) These engines are more likely to run lean than rich. You also mentioned a hot transmission tunnel, which could mean excessively hot exhaust, which could come from a lean mixture (and combustion of fuel and air actually in the exhaust system -- manifold glowing red, etc.) The thing about having a separate temp sensor for the gauge and for the fuel injection is actually fairly common design for an older car. Even my 1992 Saturn and my 1994 Mazda have separate sensors. You should be concerned if your mechanic doesn't know/suspect this sort of thing. Before we can provide much help to you, you're going to have to learn your engine. There is no better way than to sit down on a slow day with Nissan's factory service manual, which is the very best reference for your car, and which is free for you to download. There are a lot of acronyms we throw around, and they're essential to the discussion. And when we talk about parts, you have to know where they are on the engine. The part of the FSM (factory service manual) you need to read is section EF ("engine fuel"). Also study this thread: http://www.classiczcars.com/topic/26501-sticky-efi-thread-please-chip-in-fi-guys/

Well, it MIGHT get you over the hump, but there's a lot more heat in those injectors than in the fuel rail! In my experience, the vapor in the lines clears pretty fast anyway, judging from the sound of the pump -- maybe 3-4 seconds. And FWIW, I believe someone else tried a priming switch too -- didn't help them either.