SteveJ

Dang it. My bad. I did a crappy job of tracing it. I only followed it up to Pin 5 on the ECU and assumed that the ground when from Pin 5 to ground through the ECU chassis. Thank you for the correction.

Okay, now that you have torn up everything and gotten yourself frustrated, let's see if we can put you back on the right path. Most people monkey around with the interlock relay to try to fool it. I believe there is an easier way. The emergency switch will bypass it nicely. As a test: 1. Unplug the emergency switch from the engine harness. 2. Locate the blue wire and the yellow/black (stripe) wire. 3. Use a short length of 12 AWG wire and jumper those wires together at the plug. 4. Try starting your car. By the way, the scary part of your pictures is seeing the splicing in there. I wonder what the PO was doing. Also, it looks from your fusebox that you have a late 260Z. If you don't mind sharing, what is the build date on the VIN tag in the door jamb? I have found that Nissan moved some components around between the early and late 260Zs. If people don't know you have a late car, they may tell you to look in the wrong place for certain components.

Actually, what I should have said is that the ECU provides the ground for the fuel pump relay.

If you were in the states, I would say Ace Hardware since they have a good collection of springs.

Well, what all are you thinking of doing with the swap? The ECU controls the electric fuel pump. If you keep the electric fuel pump, you would need to add your own relay control for it since the fuel pump is triggered by the AFM in the 77. You would also have to reduce the pressure, too. If you disabled the electric pump, you would need to remove the blocking plate and add a mechanical fuel pump.

Heck, Leon. I'd just push a button as the first test with a 74. I'd be willing to bet money that the interlock is what is dropping the voltage to the solenoid, too.

Do the research first in the FSM. You will see what you should try next.

That's the one I bought. I found mine on eBay.

I bought an abrasive blaster at Tractor Supply. I just have to get around to trying it out. By the way, Blue, what did you and the good Captain find out when digging through the flattops? A friend gave me another set recently.

Welcome. Start searching on here about waking up a car that has been sitting for a while. The 74 also has a "safety feature" not on any other year Z. Search through these results to see what I mean. seatbelt interlock site:classiczcars.com - Google Search

I think the key to this is the fact that it's a 74. Search through these results: seatbelt interlock site:classiczcars.com - Google Search Also download the FSM from XenonS30. Go to the BE section and start reading on page 30.

Thanks, Leon. I couldn't remember the name of the other one. I have that hiding in my garage somewhere, though I'm sure it's not sitting next to the Unisyn.

Fuel? Fuel? Get an inline fuel pressure gauge. One that reads 50 psi is fine. See if you get/have pressure in your fuel line. *CAUTION* Read through the FSM and see the proper way to depressurize the fuel line before you attempt to install a fuel pressure gauge. If you have good fuel pressure, start going through the EF section of the FSM and read through the Fuel Injection Bible. (Find that at XenonS30.com.)

Edelbrock 4027 UNI-SYN CARB. BALANCING : Amazon.com : Automotive unisyn | eBay https://www.google.com/search?hl=en&tbm=shop&q=unisyn&oq=unisyn&gs_l=products-cc.3...1930.3858.0.4089.10.7.2.1.1.0.105.550.5j2.7.0...0.0...1ac.1.Vesar73IZTo#hl=en&tbm=shop&sclient=psy-ab&q=unisyn+carburetor&oq=unisyn+carburetor&gs_l=serp.3...3531.7257.0.7503.11.11.0.0.0.0.350.1329.8j1j1j1.11.0...0.0...1c.1.8.psy-ab.A45yZF7kDro&pbx=1&bav=on.2,or.r_qf.&bvm=bv.44990110,d.eWU&fp=4ae7c0460bab4d43&biw=1680&bih=884 Take your pick

Mike, thanks for adding your input. I totally misread the initial post. Yes, the side markers are part of the taillight circuit. Somehow I got it into my head he was talking about the turn signals. If it is the parking lights, that is on page BE-13.

I'm glad you like my advice. I'm full of it...Hmm, that didn't sound right. Anyway, if it's not corrosion, I suggest a divide and conquer approach for narrowing down a short. Break the circuit into three sections: front, back and dash. That would be at connector C-3 and at the turn signal switch. Test each of them for a short by checking resistance from the positive side of the circuit to the chassis ground. Take the bulbs out to prevent false positives. Report the resistance readings if it's not obvious where you should go next.

Okay, I had to look. I can't find the Lockworks brand mentioned in the linked post, but searching for door locks for an 81 Maxima on Autozone came up with Locksmart DL47010.

There are several points where you can break the circuit. HOWEVER, before you do that, check all of the sockets on that side for corrosion. That is very common on our old cars. Clean out the corrosion as needed and coat with dielectric grease to reduce the chances of it coming back. After that go to the FSM. Look in the BE section, especially focusing on BE-10. That breaks down the circuit and gives you an idea of where all of the connections are. Please use an ohmmeter to find the short. Jumpering out the fuse can cause an electrical fire. The way short circuits typically develop (not all inclusive): 1. Corrosion in the sockets 2. Bad rewiring 3. Rubbing or other degredation in the insulation (Other degredation can include heat from the environment or electrical current.) 4. Working on another component and damaging the wiring.

Frankly, I don't remember seeing a return spring on either my 73 or 74.

Dielectric grease to hold the ball in place - and only a tiny dab.

Turn signal switches can be had at a reasonable cost. I have a big box of them. All they need is for me to tag & test them. Unfortunately the pot metal is an issue. I don't have any broken switches handy to try to engineer a solution. (By the way, if any of you have a broken switch to donate to the cause, I will take it.)

Also Hazard Switch ? Brake Light ? Turn Signal Circuit Analysis | Fiddling With Z Cars Early Hazard Switch | Fiddling With Z Cars Turn Signal Repair | Fiddling With Z Cars

Another alternative is to tap the end of the wrench with a brass hammer.

Based on a thread over at zdriver.com, Robert has an automatic. I suggested there that he look at the neutral safety switch as a possible culprit.

Look at page ER-3 in the 74 FSM and ER-4 in the 75 FSM, that gives you a general idea. The problem with following the FSMs is that most cars have the engine slingers removed. They were located on the front passenger side and rear driver side. IIRC, there is a threaded hole in the head for the front one, and the rear one was on the back stud for the exhaust manifold.