1977 FSM not helping.

[Zed Head]

The ECU opens the injectors after it sees three sparks, from the coil (the ECU has to see the "fire" to know when to give the "fuel"). You can have spark, but no gas from the injectors, if the ECU does not get the signal from the coil, to open the injectors.

The cold start valve will supply enough gas to start the engine but stops supplying gas when the key is not at the Start position.

The details of how the EFI system works are explained in full in the Engine Fuel section of the FSM.

Edit - forgot one important thing: the ECU opens the injectors by grounding the circuit. If you don't have 12 volts at the injector plug with the key at Run or On, the injectors will never open. That's why I asked if you have 12 volts at the injector plug with the key On.

Edited December 20, 2011 by Zed Head

[Inthenameofweez]

Omg. Everything makes sense now. I understand what you mean with the coil/cold start valve.

So while I'm reading... what is your opinion as to why the injectors won't open? Bad/no signal from the coil?

Edit: No. That can't be it. I've got 12V at pin 1...

Edited December 20, 2011 by Inthenameofweez

[Zed Head]

Pull an injector plug and check for 12 volts there. Both sides will have 12 volts. Current flows when the ECU lets it, causing the injector solenoid to move.

[Inthenameofweez]

I've got a node light.

Gonna go play with it tonight. You're absolutely right. I pulled the cold start valve and it just cranks. I've also got a new battery. I'll be back online in a bit...

[Inthenameofweez]

Here are some pictures of what I'm working with.

There are 3 good fusible links. I have cleaned and verified that full continuity exists. The 4th one has been ghetto rigged because it obviously burned itself to death and melted the plastic case and wiring itself.

I have questions about a few different issues.... Right now I have no dash lights, and no "BRAKE" or Battery light indicators. Before I started repairing things (main relay and fuel pump) I had blue/green dash lights and the previously mentioned indicators would light.

Also, where does the lead from Pin 1 of the ECU connect to the ignition coil? I have verified that the fusible link controlling this wire is good, but I have not verified that the connection is good. I will include some pictures. Please give me a hint.

Furthermore, there is a small blue capacitor looking unit next to the coil that had a wire disconnected from it. I have since soldered it back into place, but it changed nothing. What does this little cylinder do? And is it a replaceable part? Again, I'm really starting to suspect an issue with the ignition switch because I have no dash lights, the indicators no longer illuminate. Also, while testing at Pin 10 at the ECU, I only have 12V while in "ACC".

I used a node light tonight and found voltage being sent to the cold start valve NO PROBLEM. However, there is no injector power. Zed Head, you mentioned a tachometer issue could cause no injector power. I am going to start reading the Body Electrical section, but in the mean time, could you expand on this issue?

I'm am leaving the car for Christmas break (heading home) so I will not be able to work on it for a week. As I'm sure all of you will have family events during this next week, so I do not to hear a response for a while. However, even if you've got just a few thoughts, please share them.

You can also see that the green fusible link seen in newer year Zs is not present on this car. This was manufactured in 2/77.

Thank you again Datsun junkies and have a good holiday break from school and work.

[Inthenameofweez]

So, I found a common link between all of my issues. The ignition relay.

Sure enough:

So i tried to repair the ground with some solder of my own:

I got the dash lights working. Brake indicator and tach are now working. Still no fuel indicator though. And no fuel injector pulse. I heard some shorting, and unfortunately I let the internal positive cables of the relay touch the negative body of the relay. And it burned the relay up. So I'm hoping that a new relay will solve all of these issue. Not sure what else could be causing no injector pulse.

I just hope I don't have the same issues as this guy: http://forums.hybridz.org/index.php/topic/72897-280z-ignition-relay/

Until next year!!! That's all the wrote.

Edited December 21, 2011 by Inthenameofweez

[SteveJ]

Well, I can see how someone pretty much hacked away at the fusible links. That'll cause you some issues right there. It might be a good time to source a used engine wiring harness...

[Zed Head]

In Post #29, n your first picture, that white thing with all of the wires attached is your ballast resistor. The blue wire is attached at the post on the far right. I think that you've already tested it though, but it wouldn't hurt to check again.

In the second picture, off of the positive post of the battery there is a second small wire with a green wire spliced in. That green wire is where the green fusible link would be, but it looks like someone may have replaced it with plain old wire. The connections get rotten so someone may have "fixed" it in the past. You should put a fuse or link back in that spot to save your EFI components.

It would still be worth your time to pull an injector connector and measure voltage, or use your noid light to connect one side to ground. If you have voltage, the noid light will light. No power at the plug, no injector opening.

The early ZXes have a similar relay that will work also. The only difference is an extra, separate ground terminal, the plug and the internals are the same. The Z relays like yours ground through the case.

[Inthenameofweez]

I got a new ignition relay in there and no change. Brand new battery as well. Gauge lights work, engine cranks, and spark is there. I'm going to replace plugs and check compression just as a maintenance item.

Noid light still not lighting on the individual injectors. Bu the cold start injector lights like a GD Christmas tree. And I know it's spraying fuel because I'll get a random fire from that fuel working its way into the cylinders...

Help? I wanna drive this damn thing!