SteveJ

OEM pump: https://www.courtesyparts.com/oem-parts/nissan-pump-assu-fuel-17011p7211?c=cT0xNzAxMS1ZODAwMA%3D%3D

From the factory there is a sheet of plastic between the door and the door card. It basically goes around the perimeter of the door where you see the red and black line below. To replicate what the factory had, get some butyl tape like this: https://www.amazon.com/Sealant-PROMOTOR-Sealants-Installing-Windshield/dp/B095NMPNZ3 and create a border as shown above. Take a large sheet of 5 mil or thicker and adhere it to the butyl tape. Trim.

Thank you for being willing to reconsider the inhibitor switch. I had a feeling it could be your culprit after what I saw on my friend's car. Starting on page AT-49 in the FSM (page 314 of the huge PDF), you'll see the procedure for testing/adjusting the inhibitor switch.

Fuse size depends the gauge of the wire you're protecting. I recommend 10A for 14 AWG, 20A for 10 AWG or 12AWG and 7.5A for 16 AWG or 18 AWG. Don't forget about maxifuses or fusible links for the system as a whole. As I searched for vendors for wires with colored stripes, I found this place was probably about the most economical and flexible: https://www.sherco-auto.com/striped-tracer-wire.html You may be able to adapt this for fusible links: https://www.amazon.com/1J0937617D-Battery-Terminal-Volkswagen-Octavia/dp/B0863XLF6R As for current draw, let the factory fuse box be your guide to start. The fan is the highest draw, especially if you have AC. While the parking/tail light fuse is 20A, you can go to 10A and 14 AWG with LEDs. (IMHO the engineers undersized the wire in this circuit for incandescent bulbs.) The same goes for the flasher. The Common fuse is for the cigarette lighter. That can drop to 10A. I'm not positive about the draw on the wipers, but if you keep it at 20A, I would use 12 AWG instead of 14 AWG. The brake light circuit can also go to 10A with LEDs. Note: the fuse ratings I wrote are very much on the conservative side. However, I have seen enough melted fuse boxes and melted connectors that I prefer a conservative approach. As for wire sizes here is a rule of thumb. The wires for the large connectors should be 14 AWG. Use 16 AWG for the smaller connectors. On the 73 (and on through 76), Nissan started using the 9 pin connector on the headlight switch. That was a bad move. The connectors were undersized for the current of the parking lights, and that connector would melt down. For the large bullets, I would use 10 AWG. Consider trying 8 AWG for the circuits for the ammeter. Are you sticking with the ammeter or are you going to have a voltmeter instead?

So, what you need to do is test for voltage to ground at the black/yellow wire at the ignition switch while trying to start the car. This is why it can be handy to have a test lead with a clip so that can be clipped to a ground while you hold your probe on the back side of the ignition switch and turn the key...unless you have 3 arms.

I got new tires for the 260Z in preparation for ZCON. After that, I drove over to meet a couple of friends at Caffeine and Chrome. It's nice when you can get a 240Z, 260Z, and 280Z together at a meet.

There are 4 wires total. Two go to the start circuit.

By the way, you better be planning on attending ZCON.

Thank you for following up. It's good to know the resolution.

Even better price on the adapter: https://www.glowshiftdirect.com/1-8-bspt-male-to-1-8-27-npt-female-hex-thread-adapter/

The rule of thumb I heard is 10PSI per 1K RPM. Of course, without a mechanical gauge, it's difficult to know for sure. If you're worried enough about it, you could get an adapter like this: https://www.pegasusautoracing.com/productdetails.asp?RecID=11217 and add a 1/8 NPT mechanical gauge.

Here's a photo of the electronic flasher relay in my 73. You can see the ground wire I added on the 3rd terminal.

You may consider changing out your old electromechanical flasher relay with an electronic relay like this: https://www.amazon.com/gp/product/B0811GTVH2/ It has a speed adjustment that I like. The thing is that you'll have to run a ground wire to it to make it work.

I think we could make a meme of that, Alan.

Are you familiar with George Washington's axe? Someone is selling George Washington's original axe. The handle has only been replaced 5 times, and the head only 3 times. So I guess if you took the original East African Safari winner, replaced every single part & converted it to left hand drive, the video could have been using the original.

I never had tach issues with ZX ignition in my 260Z. (Same general design as the 280Z tachometer circuit.) It was modified by a PO. I eventually bypassed the ballast resistor and using a coil with similar impedance as a 280ZX coil with an E12-80 module. No problems. I'm not sure what you mean with respect to adding a resistor in addition to the one that's in the circuit.

Has your fuel pressure decreased causing a lean condition? Lean=hot

Start with the wiring diagram from the FSM: It shows one wire coming from the fuse box: blue. There is another wire coming from the resistor: blue/white. The wiring diagram shows this as yellow/white. Finally there is a ground wire. From this approach, the first thing to check is quality of the ground. Measure resistance to ground on connector on the dash harness side at the black wire. Also make sure there is no resistance from the connector on the gauge to the gauge body. Clean the connector with Caig Deoxit while you're at it. Next, as I stated before, check the resistance from the blue/white (or yellow/white) wire at the dash connector to the negative post of the coil. You may need to make an extended lead with an alligator clip to reach. You can build your own probe with something like this: https://www.amazon.com/Insulated-Multimeter-Stackable-Connectors-Adapters/dp/B07C535GBD. Also make sure the dash to engine harness connectors are clean.

Was that with the key in ON? If so, move to the other tests. If not, re-test with the key in ON. What we are trying to figure out is why you're not seeing voltage to the relay that completes the circuit for the solenoid. If we don't find voltage on the downstream side of the ignition relay, we need to test to see if you have voltage going into the ignition relay. After finding faulty components, we can replace just those components. The goal of this is to fix with spending the least amount in replacement parts. Did I understand that you replaced the ignition relay? If so, where did you get the replacement?

The junction between the dash harness and engine harness is in the passenger footwell. C4 is a white connector. You want to work your probe in on the back of the connector so you can measure voltage while it is connected. It should be at the block marked 3 in the picture, though many people have removed that junction block, especially if they installed aftermarket AC.

Thank you for the feedback. So the inhibitor switch may not be the immediate problem, but we haven't ruled it out. Have you checked for voltage to ground on the white/black wire at connector C4 with the key in ON? Also check for voltage to ground on the black/white wire with the key in START.

You may have missed my other reply. Try starting the car in neutral and report back to us.

Trace the power for the coil on the relay at the top of the image you clipped. The white/black wire comes from the inhibit switch on the transmission, and if you trace the white/black on the other side of the inhibit switch, you'll find it goes back to the ignition relay. The OP has an automatic. He has posted on starting issues before.

I'm curious. Have you tried to start the car with it in neutral? Recently a friend with a black/gold 10AE said his starter gave out. I told him that before he orders a starter, he should verify he had voltage at the solenoid. He measured and said he had no voltage there. I went to his house with a remote starter. I verified his reading and used the remote starter to start his car. After consulting the wiring diagram, I traced it back to an ignition relay and verified the coil was not getting power. That led me to suspect the inhibit switch on the transmission. I told him to put the car in neutral and try starting. It started right up. I don't recall seeing anything in this thread about trying to start in neutral. Try it and report back.

Typically the condenser suppresses noise with the rapid changes in the magnetic field of the coil. Interestingly enough, the 260Z does not have a condenser in the wiring diagram for the ignition. I'm not sure why. The 1980 has the condenser on the positive side of the coil (E12-80 ignition module). My thought is that if the resistance is too high between the ignition module and tachometer, your tachometer isn't getting the signal it needs to react. Also, if the blue wire for the TIU is coming into contact with another wire (or is connected to the TIU still), that could affect the signal quality going to the tachometer. We know the blue wire for the TIU isn't solidly grounded, otherwise your car wouldn't start/run. A few years ago, a friend brought over a customer's 260Z that wasn't running that well after a ZX distributor swap. I don't recall if he said whether or not there were tach issues. The first question I asked was, "Did you disconnect the TIU?" After a Homer Simpson "D'OH!" he disconnected the TIU, and all was good. You may consider adding a meter like this to your arsenal: https://www.amazon.com/gp/product/B0002LZU7K Among other features, it has a tachometer. That can make for better troubleshooting and analysis, not only for this problem, but for tuning issues, too.