SteveJ

I'm not sure if the connector on the other TIU lines up. Do you feel adventurous enough to modify the ignition? With an HEI ignition module, a couple of diodes, a heat sink, heat sink paste, and a connector from Vintage connections, you could make a replacement ignition unit that would be pretty darn reliable for about half the price of that TIU you have in the last photo. (@Zed Head are saying the same thing.) Here is how you would wire the HEI for the TIU connector in the 260Z with the 6 pin rectangular connector. (Edit: Changed for the revised diagram in my later post.) Note: the connector as I have is drawn is a mirror image to the connector shown in the FSM wiring diagram per the Nissan drawing practices.

No, the relay won't work in the 78.

But, but, but...they have been touched by the guys working at Gas Monkey Garage! 🙄

You would want to test it the way I described. Your testing would not yield good results. With the ignition in ON, you would see voltage to ground at the positive and negative on the coil, except when the TIU is triggered by the distributor. (This is on a properly wired/functioning ignition.) For a stock configuration, it should be a white/black wire on the positive. The blue is on negative, as in your photo. The white black should go to the ballast resistor. There should be a black/blue on the middle terminal of the resistor (starting) and black/white on the opposite end of the resistor (running). The TIU is in the passenger footwell, likely on the firewall. Now, for the stray wire in your photo, you would have to clean it off enough to tell me what the wire color(s) is. My first guess is that it might be one of the wires that goes to the ballast resistor.

You said you're not an electrician, and now you're making me break out the electrical engineer. The coil is a step-up transformer. You are going from 12VDC up to 30,000 VDC or higher. The higher voltage will be induced when you have a complete circuit on the 12VDC side. However, if you have a complete circuit all of the time, you won't develop the magnetic fields on the primary side to induce the voltage on the high voltage side. When the engine is turning, the reluctor passes near the pick up coil in the distributor, and it creates a signal for the Transistor Ignition Unit to ground the blue wire. Current flows, a magnetic field is developed on the primary side, a voltage is induced on the secondary side, that induced voltage is at a high enough potential to overcome the resistant at the gap at the spark plug, and you have your spark. Now don't worry about much of anything in the previous paragraph until you REALLY want to understand ignition systems. With how you measured, you don't have power on either side of the coil. Power is voltage and current. You measured voltage on both sides of the coil. No, I'm not being pedantic. I hope this comes clear in a minute. In it's normal state, the ignition system is an OPEN circuit. With the key in the ON or START position, you are connecting it to the positive side of the battery. There is nothing connecting the ignition circuit to the negative side of the battery (ground) until the TIU connects it to ground. The primary side of the coil is just a long piece of wire, so it will have essentially the same potential at any point in that circuit. So the short answer is that you are using the meter properly, and you're probably seeing the voltage you should be seeing. If you are wondering whether or not the TIU is working, pull the coil wire off the distributor, with the coil wire connected to the coil. Position it close to one of the bolts on the shock tower (like about a 1/4 inch or so). Try to start the car. You should see the spark jump between the coil wire and shock tower.

Charles has a good point, Shawn. Start with the easy stuff first. That would be the first paragraph in post #6. It sounds like the electric fuel pump operation will be more challenging for you to diagnose, but that's okay. Also, let's pause to talk about safety. There is a good chance you'll be needing to work around the gas tank. Do you have access to a lift or solid jack stands? Jack stand points are shown in the FSM. Wear safety glasses to keep all of that old grease out of your eyes, and your Covid mask will keep that crap out of your mouth (experience talking here). If you need to replace the hoses in the tank, drain the gas tank. There is a drain plug on the tank. Just make sure you have enough storage to catch the gas. I like using a huge oil catch pan (5 gallon) and have a couple of 5 gallon gas cans in case the tank was pretty full. Have plenty of 5/16 fuel line (low pressure fuel line will work). If you remove lines, do it section by section so you don't accidentally mix up your supply and return from the tank. As I mentioned before, if the fuel line around the electric fuel pump has never been touched, it is definitely old and brittle. When I dropped the tank to remove the rear bumper many years ago, those lines snapped like dried twigs. Have compressed air available to blow out the hard lines, too. It doesn't hurt. You may need to drop the tank and clean it out, too. That is a technically easy but time consuming process the first time you do it.

The resistor value is 2.2kOhms.

The relays are at the passenger kick panel near the fuse box. They are most easily identified by matching the wiring diagram to the relays.

Yes, there are things not covered in the manuals. Trust me. I've spent years reading posts on this site and others to learn. However, do not discount what is in those manuals, such as the location of the filter and the relays. 😉 Your fuel problems could be anything from junk in the tank, to a clogged filter or pump, to a cracked hose that lets air into the system. The maps for most of the things you want to test/inspect are in the FSM. For the filter, look at page FE-7, just don't look for the word filter. The relays can be more of a challenge to test, but they can be tested. You'll need a voltage source (a 9 volt battery can work for this) and a multimeter set to resistance to check the contacts. You use the voltage source to activate the relay and ensure the contacts operate properly. When you have the materials together to test, we can go more into the details of testing. That way you don't have to search through as many posts. Also familiarize yourself on how relays work if you haven't played with them before. https://www.explainthatstuff.com/howrelayswork.html As for the asbestos, yes, the insulation on the fuel rail is asbestos. It's mostly a sleeping dog. If you don't disturb it, nothing happens. If you need to move it some, wet it down well before touching it so it doesn't throw off as many fibers.

We could always just use a larger font to reply to you. I feel like I'm talking to an old man. 😉 Note, that the default font size is 8 point. @MikeSo many of us here are old farts, can you make the default font size 12 or 14?

From the factory it started with the 74. The factory had a retrofit kit for the 73 that has the same design for the electric fuel pump...for the same problem (vapor lock). That kit was also when wrapping the fuel rail started, and that's genuine asbestos on the fuel rail, too. You have presumed much, but what have you diagnosed? What is the fuel pressure? Have you inspected ALL of the fuel hoses from the tank to the mechanical fuel pump? What is the condition of the fuel filter? If you haven't found the electric fuel pump, you probably haven't found the filter. As for the electric fuel pump, is the wiring intact? Is the pump still installed? Are the relays working? If it's a bad relay, it's a much cheaper fix than replacing the fuel pump and then realizing you need to replace one (or both) of the relays. It's easy to throw parts at a problem, and it's easy to get frustrated when you realize you have spent a fair amount of money without solving the problem. I ask a lot of questions and tell you to read the FSM because I want you to fix the car right and as cheaply as possible. You have better things to do with your money than waste it on a wild goose chase. Pay attention to the questions and post answers. If you don't understand the question or how to get the information to answer the question, ask. Just put some effort into it. You'll learn a lot, and you'll get a lot of help.

It should run without the pump working. Lord knows my 73 did (ran until parked...). However, that is only if the rest of the fuel system is fine. Symptoms of the bad pump could be low fuel pressure or hard starting when the car is hot (vapor lock). It's not that hard to change, but you better have something to clamp off the line. It might be better to diagnose the system than just throwing parts at it. Maybe even bench test the old fuel pump. Here's what it looks like: https://www.google.com/search?q=260z+electric+fuel+pump&sxsrf=ALeKk00okqF6AEt_qSB308PAhruYMtew0Q:1622676245782&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiQ9tuJjPrwAhUvU98KHePYB-UQ_AUoAnoECAEQBA&biw=1920&bih=880 Of course, if the fuel lines back there are old, expect to have to replace them. The stock hoses were formed hoses so you have to get some 5/16 metal elbows with extra hose clamps or have long lazy bends to prevent cutting off fuel because the hoses are kinked.

Did you think I would steer you wrong? I think Tony D was posting about the VW fuel injection relay over at Zcar.com back around the turn of the century. I'm a vast repository of useless trivia, but sometimes some useful information sticks, too.

Um, yeah. I said that a couple of times about the vent line. Find the electric fuel pump...https://www.classiczcars.com/files/category/12-260z/

Post a photo of your brake booster. According to the parts fiche, your booster should be like the 240Z/260Z booster if your car is not a 2+2. part # model applied date qty interchange superceded from to newer former ASSY-MASTER VAC 6INC 47210-E4600 7105 1 47210-E4601 7106 7108 1 47210-E4600 47210-E8700 7109 7206 1 No No 47210-E4601 ASSY-MASTER VAC 7 1/ 47210-N3001 1 Yes Yes 47210-N3000 47210-N3000 7207 7507 1 No No 47210-E8700 The 280Z booster is on the left. The earlier booster is on the right.

Not if it's stock. Like I said, download the factory service manual and read sections EF and FE.

I'm not sure what your question is. Why couldn't it have a mechanical and electrical fuel pump?

You have a return line. I see a hose attached to it. Like I said before, the capped off line is a vent line for evaporative emissions. If the car is in stock configuration, it has both a mechanical and an electrical fuel pump. Download a copy of the FSM. The link is in my signature. (Hopefully you're not using a phone for this site. You miss out on some good features.) The EF and FE sections have a lot of information on the fuel system in your car. In the meantime, you may want to start tracking down answers to my questions, or pose some questions in response to help bridge the gaps in your knowledge. Continue to figure out what the previous owner(s) changed and document it. Then you can figure out how to make it work right again.

Actually, the red cap is blocking off the vent line. That should go to the carbon cannister The middle line is the return. When is the car sputtering? How have you ascertained there is no fuel flow? Have you put a fuel pressure gauge between the fuel rail and one of the carburetors? How old are the fuel lines? Is the electric fuel pump running? Is the electric fuel pump installed? What is the condition of the fuel filter?

Welcome to the club. We tend to look smarter after we get done wasting our time on dumb things. And thank you for providing your solution. You might be helping someone else in the future.

I marked the TIU. Make sure it is unplugged. The resistor is wrapped in tape. It should be on a blue wire on the engine harness side of the C4 connector. Depending upon how the MSD ignition was wired into the car, that could be affecting your tach signal, too. If you haven't done so already, visit the Resources section of this website and find the factory service manual for the 260Z. (Hint - Look at my signature for a shortcut.) It can help you a lot. For instance, the tachometer wiring schematic can be found on page BE-33.

Considering the 260Z has a Transistor Ignition Unit (TIU), I would call an MSD-6A a change from stock. Is the car running right? If not, that could mean the TIU was not unplugged. That could mess with the tach, too. By the way, a friend got his 260Z tach serviced by Bob's Speedometer (https://www.bobsspeedometer.com/), and he was pleased with how the tach operated after that.

The 260Z tach is essentially the same as the 280Z tach, including the wiring. Don't forget to check the resistor in the circuit. It's over in the passenger footwell area.

Exactly...

IIRC, it's squeeze on the sides and pull.