Gremlins in my Fairlady's Ignition System

[dasmoover]

New to the world of Datsun/Nissan.

I'm working on a 1977 280Z.

Currently having an issue with spark.

No spark to the spark plugs.

I have read through the FSM/EFI Bible.

The coil has been replaced (then swapped back to stock unit only 35k miles), ECU has been replaced, battery has been replaced.

Fusable links have been replaced and all get spark on both ends. Headlights work.

Checked fuse panel under passenger kick - none blown.

Cleaned all electrical connections and grounds with C&C.

I am getting spark from the ballast resistor and to the + and - on the coil with ignition on. Have not tested while cranking.

Engine cranks no problem, fuel gets to the injectors, engine won't start.

Symptoms: With ignition on door buzzer does not sound. Hazards and turn signals DO NOT WORK.

RPM Gauge does not move at all when attempting to crank.

Back-Story: Bought the car with 35k miles. Ran only off cold start then died when kicking over to EFI.

Towed it home, started it a few times, battery had died. The original battery had an acid leak and gunked up the terminals.

Cleaned the terminals up a bit. In the mean-time I put a battery in from my 84 300zx. Attached the terminals.

I flicked on the engine bay light and my fusable links sparked and sparked the wire going to the condenser on ALT.

I did not attempt to turn over the car. I removed the terminals and the battery immediately. Bought a new one and put it in.

All lights work, but now the hazards/turn signals/spark/door buzzer is gone. Replaced all fusable links and confirmed voltage on both sides.

Could I have also blown my Transistor Ignition Unit or my Ignition Module?

Thanks for any input, it's been about a month and I've only narrowed down my possibilities. It thought I damaged my ECU,

now i'm thinking either one of those two components are failing OR there is a short somewhere near the battery terminals or inside the harness itself.

All the fuses are fine and the relays all click for fuel pump/injectors.

Lead ignition wire is connected.

I have identified and cleaned all the electrical connections on both sides of the front end, nothing obvious is loose or shorted.

There is ONE blue "L" wire disconnected near my ignition coil. Attached are some photos.

Any input would be appreciated.

[SteveJ]

What is the voltage from the positive terminal of the coil to chassis when trying to start the car?

What is the resistance from the postive terminal of the coil to negative terminal? What is the resistance from the center post of the coil to the negative terminal?

Remove the coil wire from the distributor cap and look for signs of deterioration or burning. Remove the distributor cap and look at the contacts in the cap and the contacts on the rotor.

[dasmoover]

I will post back with more photos. The plastic cap on the coil spark wire is covered with golden dust. There is no burning, just very small metal shards, very clean and shiny otherwise.

Thank you for the tips. The positive terminal read 8V on the coil with ignition on. I have yet to test while cranking.

[SteveJ]

The 8V reading is about right. The voltage gets dropped by the ballast resistor.

[SteveJ]

Also, if you think the transistor ignition unit is bad, you can get an HEI module pretty cheap and wire that in for testing.

[dasmoover]

I don't want to continue shotgunning new parts in. I want to find the source of all my symptoms. The brake light comes on when the ignition switch is set to ON but still no turn signals.

How do you test resistance for these things? - What is the resistance from the postive terminal of the coil to negative terminal? What is the resistance from the center post of the coil to the negative terminal?

[SteveJ]

You test for resistance with an ohmmeter. A typical multimeter will test for resistance, as well. You compare the ratio between the new readings. It will be about the inverse of the ratio of primary to secondary voltage for the coil. The primary voltage is 12 VDC. If the secondary is supposed to be 20,000 VDC, that ratio is 1:1667. Therefore you would expect the resistance on the primary side to be 1,667 times the resistance of the secondary side. Transformer - Wikipedia, the free encyclopedia

I never said anything about shotgunning new parts in. I told you to try an HEI if you thought the transistor ignition unit was bad. You can get an HEI for about $15 + S&H from Rockauto. I doubt you can find a tester for the transistor ignition unit anymore, and $20 is much less than taking the unit to an old Datsun mechanic if you can even find an old Datsun mechanic. I also gave you trouble shooting steps to eliminate other possibilities.

[Zed Head]

Did you actually check for spark with a spark plug on the end of a plug wire or are you assuming because you have fuel in the fuel rail and nothing happens?

The one disconnected L (blue) wire might be the signal wire to the ECU to fire the injectors. It should be connected to the same post as the wire to the negative terminal of the coil at the ballast resistor. Without that wire, no signal to the ECU, no injectors spraying fuel. Maybe. Your picture doesn't show where the wire ends are, which is the important part.

[dasmoover]

You test for resistance with an ohmmeter. A typical multimeter will test for resistance, as well. You compare the ratio between the new readings. It will be about the inverse of the ratio of primary to secondary voltage for the coil. The primary voltage is 12 VDC. If the secondary is supposed to be 20,000 VDC, that ratio is 1:1667. Therefore you would expect the resistance on the primary side to be 1,667 times the resistance of the secondary side. Transformer - Wikipedia, the free encyclopedia

I never said anything about shotgunning new parts in. I told you to try an HEI if you thought the transistor ignition unit was bad. You can get an HEI for about $15 + S&H from Rockauto. I doubt you can find a tester for the transistor ignition unit anymore, and $20 is much less than taking the unit to an old Datsun mechanic if you can even find an old Datsun mechanic. I also gave you trouble shooting steps to eliminate other possibilities.

Thank you so much for the test ideas! Do you mind sending a link to the correct HEI module? Worth a test for the price.

Zed Head: I will take more photos tomorrow. The blue wire comes from the main wire harness. I checked a spark plug for spark, no good.

The blue wire could be responsible for failure switching over to EFI after cold start valve bypass. Thank you!

I know i'm not getting spark at the moment.

I will be able to conduct all the tests tomorrow.

[SteveJ]

Look at a 1982 Celebrity with a 2.8L V6 @ Rockauto.com. Here is one part number: AIRTEX / WELLS Part # 5A4.

You want a four pin HEI. Then Google HEI 280Z and look at the images. Be sure to unplug the transistor ignition unit in the car when you hook up the HEI.

Have you tried spraying in starting fluid to make double sure that it is a lack of spark and not a lack of fuel?

Of course, this does assume that a previous owner did not swap in a 280ZX distributor. Post pictures of your distributor to confirm.

Edited July 2, 2014 by SteveJ

[dasmoover]

I have done the starter fluid test to no avail and the car is basically bone stock.

[Zed Head]

I think that blue wire is the key. I didn't go in to all of the details of the blue wire but it also runs to the ignition module and the tachometer, branching off to each along the way.

I think that you should check the wiring diagram and get that blue wire connected to where it should be, before buying any parts. Does your tachometer move when you're cranking the engine? That would be a clue.

Here's a picture and a link to its source. It's 1976 but 1977 is essentially the same.

http://www.classiczcars.com/forums/open-s30-z-discussions/36494-free-full-color-wiring-diagram-1976-280z.html