Two white/red wires that came from the fusible link box towards the front of the car. Which one looks bad and or burned? The thick white/red wires feeds multiple circuits from my research. One of these is why I have starting problems, again.

I see some corrosion, but for a car that's about 50 years old, that's not unusual.

8 hours ago, dtejada said:

. One of these is why I have starting problems, again.

Are you sure? Do you have a cranking problem, or a fueling problem, or a sparking problem?

I think I see the evidence of a wire nut on the thick one. Regardless, if it's not connected it's a problem.

4 hours ago, Zed Head said:

Are you sure? Do you have a cranking problem, or a fueling problem, or a sparking problem?

I think I see the evidence of a wire nut on the thick one. Regardless, if it's not connected it's a problem.

Not so sure. Originally the fusible links had been bypassed with wire nuts. I removed those and installed a Stinger maxi-fuse box and cut the wires back to clean copper before reconnecting everything. After that repair the car started and ran and the interior fuse box now has full power on all fuses.

Right now the engine cranks normally and the fuel pump runs. Plug wires are confirmed in the correct firing order (1-5-3-6-2-4). I didn’t change anything else electrically other than pulling the plug wires one at a time and reinstalling them.

The only lights that currently don’t work are the parking lights / dash illumination. I checked the TAIL fuse and there is voltage on both sides of the fuse clips with the switch on.

At the moment the engine cranks but won’t start again. Still working through the EFI system since I’m new to these cars.

Edited March 13Mar 13 by dtejada
Duplicate

9 hours ago, SteveJ said:

I see some corrosion, but for a car that's about 50 years old, that's not unusual.

Overall the car as a whole isn't in bad shape and everything is original, the only hack was the fusible link area and the fuel pump is wired directly to a switch. Make she wonder, since power has been restored if I should wire the fuel pump back into the main harness so it can work as intended. Thoughts?

Considering that most people re-wire the fuel pump with little regard for safety, I would restore it to stock. It's not as safe as having an inertia switch, but at least it will cut off the fuel pump if the engine stops running.

19 hours ago, dtejada said:

Right now the engine cranks normally and the fuel pump runs.

19 hours ago, dtejada said:

At the moment the engine cranks but won’t start again.

If the tachometer needle moves when you crank the engine then your ignition module is working. Not sure how far the needle moves at crank speed though. The ECU gets its signal to open the injectors from the same circuit that the tachometer does. The blue wire from the coil's negative post heads off to the ignition module, the tachometer and the ECU, it branches off to each. Both the ignition module and the ECU are known to fail on the 280Z's, usually they give some clues first though.

Don't overlook the "out of gas" problem. Easy to forget to look at the gauge when you're just doing garage work.

On 3/13/2026 at 4:44 PM, Zed Head said:

If the tachometer needle moves when you crank the engine then your ignition module is working. Not sure how far the needle moves at crank speed though. The ECU gets its signal to open the injectors from the same circuit that the tachometer does. The blue wire from the coil's negative post heads off to the ignition module, the tachometer and the ECU, it branches off to each. Both the ignition module and the ECU are known to fail on the 280Z's, usually they give some clues first though.

Don't overlook the "out of gas" problem. Easy to forget to look at the gauge when you're just doing garage work.

Got you—this version flows like a real forum post and still shows you actually did the work:

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Alright guys, I’m stuck on my 1977 280Z and trying to avoid going in circles. The car was running before, but it suddenly became a no-start. The last thing I was doing before it stopped starting was moving wires around near the fuse box and harness area, so I’m thinking I may have disturbed something there.

Right now the engine cranks strong but won’t fire at all. I just put about 5 gallons of fresh gas in it. The fuel pump is currently wired to a manual toggle switch, and when I turn it on I can hear it running strong and pushing fuel through the lines. Fuel is definitely reaching the engine area. The fuel gauge doesn’t work, but I don’t think that’s directly related.

On the ignition side, I do have spark. I tested using a spark plug on one of the plug wires and I can see spark. I also checked the coil and I’m getting about 12V at the positive terminal with the key on. I already cleaned up the coil terminals as well. So as far as I can tell, I have spark and fuel present.

One thing that stands out is the tach. It does not move at all while cranking, and even when the car was running before it was stuck around 2000 RPM and never moved. That makes me think there could be an issue with the distributor signal or ignition trigger.

The appears to have some hacked wiring from a previous owner based on the electrical tapped wires I see unless its stock, and like I mentioned, I was messing around in the fuse box area right before this happened. I’ve checked and I do have power at the fuse box, but I’m wondering if something in the ignition or EFI circuit got disrupted, maybe a black/white wire or something feeding the system.

At this point I feel like I have fuel, spark, and air, but the engine still won’t even try to fire. I’m starting to suspect something like the distributor pickup, a missing trigger signal to the injectors, an EFI ground issue, or possibly the ECU not firing the injectors at all.

What I really need help with is what to check next beyond the basics. Specifically how to confirm if the injectors are actually pulsing, where the main EFI grounds are on these cars, and which wires I should be checking for the trigger signal coming from the distributor. Also any way to verify the ECU is actually doing its job.

I feel like I’m close, just don’t want to keep guessing and throwing parts at it. Any direction from someone familiar with these 280Z EFI systems would really help.

16 hours ago, dtejada said:

On the ignition side, I do have spark. I tested using a spark plug on one of the plug wires and I can see spark.

16 hours ago, dtejada said:

One thing that stands out is the tach. It does not move at all while cranking, and even when the car was running before it was stuck around 2000 RPM and never moved.

16 hours ago, dtejada said:

. Specifically how to confirm if the injectors are actually pulsing,

Since you've checked for spark and have it the tachometer needle isn't necessary as a diagnostic tool.

The ECU gets the coil negative trigger signal on Pin 1 at the ECU connector. You can turn the key on check for voltage at Pin 1 to verify that.

The simple test for the injector control is test lights of some kind. NOID lights are the common one but you can use an LED test light also. Connect from pin to pin in the injector connector and try to start the engine. The light should flash.

On 3/17/2026 at 2:56 PM, Zed Head said:

Since you've checked for spark and have it the tachometer needle isn't necessary as a diagnostic tool.

The ECU gets the coil negative trigger signal on Pin 1 at the ECU connector. You can turn the key on check for voltage at Pin 1 to verify that.

The simple test for the injector control is test lights of some kind. NOID lights are the common one but you can use an LED test light also. Connect from pin to pin in the injector connector and try to start the engine. The light should flash.

Got 12v on Pin 1! Haven’t got around to test injector control, had to order a test light. But wanted to show this, how likely is this cracked AFM boot the cause of the no start? I just ordered a new boot, will be arriving Thursday.

On 2/27/2026 at 7:53 PM, dtejada said:

The car starts and runs and the EFI works

25 minutes ago, dtejada said:

how likely is this cracked AFM boot the cause of the no start? I

Seems like the main question is "what happened between then and now?" The cracked AFM hose could stop the AFM from functioning, but the engine should stil start for a few seconds on cold start injector fuel.

Maybe your spark is too weak. Are you seeing s strong blue spark or a weak yellow spark? You might try starting fluid to see if you can get it to fire for a few seconds.

Another possibility is flooded/fouled plugs. Have you pulled a spark plug to see how it looks? I'd do that, it's easy and quick.

46 minutes ago, Zed Head said:

Seems like the main question is "what happened between then and now?" The cracked AFM hose could stop the AFM from functioning, but the engine should stil start for a few seconds on cold start injector fuel.

Maybe your spark is too weak. Are you seeing s strong blue spark or a weak yellow spark? You might try starting fluid to see if you can get it to fire for a few seconds.

Another possibility is flooded/fouled plugs. Have you pulled a spark plug to see how it looks? I'd do that, it's easy and quick.

Starting fluid worked, engine fired up for two seconds. Tested injector pulse just now and drops form 12.5 to 10.4 both sides of the pin and no pulse. Tested the coil negative terminal 12.5V key on and jumping voltage while cranking.