41 minutes ago, widget777 said:

Not sure what you are asking. My phone is XXX-XXX-XXXX if you want to chat.

I advise removing your phone number from posts. That only invites scammers and spammers to track you down.

I don't think that that diagram is for a 1978.  Pre-78 Nissan did have a water temperature switch for the dual point distributors.  But 78 uses the single point distributor.  And the EGR system uses a heat activated siwtch.

The quickest way to narrow things down is to get the voltage measurements from the coil, both positive and negative posts (the coil circuit could be overheating and going open), and the injectors.  If it cranks but doesn't start those two elements are most likely to be the cause.  No spark or no fuel.

Carry the meter and/or noid lights in the car.  Measure voltages then insert a noid light if you have injector power.  A bad PCM is still a possibility.

Thank you Zed Head.

Could some of you folks tell me what voltage readings that you get on the coil posts both + and _ ? I am getting 10 volts when the battery is at 12.5 VDC. This could be why the coil is getting hot since it would be drawing more amps with a deficient voltage feed.

Thanks for your help

is the 10v when the engine is not running or running? if it is when the engine is running you could try to run a separate switch 12v wire to the coil and see if that fixes the problem. also does you coil have the correct resistance? just a thought as I am not a fuel injector person, I run carbs.

Thanks for the reply. I will check the voltage running and not running and get back to the forum.

This is the same coil that I have been running for a number of years before I have experienced this problem. I have swapped the new coil with the original one with the same problem of the engine dying. Is the resistance measured from + post to - post and what reading should be acceptable?

On 3/8/2025 at 8:23 AM, widget777 said:

Is the resistance measured from + post to - post and what reading should be acceptable?

That is the right way to measure. Resistance should be 0.84 - 1.02 ohms.

You said that you were going to measure voltage. Also, that the two coils produced the same problem.

Are you still working on the problem of the engine quitting suddenly?

Yes, I am still working on the problem. My major focus/interest at this point is determining if the coil is getting the correct voltage and checking the resistance so I appreciate your continued interest in helping a struggling Z=Brother. Thanks

Since I have the same problem with both coils, the common factor seems to be the input voltage.

Just for my clarity

1) the primary resistance is measured across the + and - posts

2) how do I measure the secondary resistance?

Secondary is from the center terminal to either of the posts.

The low voltage might indicate a problem with the ignition module. It's on the end of the negative terminal circuit. If you can contort yourself down under the dash by the fusebox you could unplug the ignition module, turn the key on, and see if you still have the big voltage drop. That is actually a big drop, like starter motor level drop.

If there's a short in the ignition module on the negative side that might also explain the hot coil. It should also cause ignition problems if the circuit doesn't get broken to create a spark.

You could also disconnect the blue wire from the coil negative terminal and see if there is still only 10 volts at the coil terminals with the key on..

Also, to be clear, when you are measuring the voltage, are you measuring from one coil post to ground?

Here's a diagram of the ignition circuit. I would also unplug the condenser and take some measurements. It seems like you might have a component failing and drawing current.

Actually, I would unplug the condenser and measure first, then disconnect the blue wire and measure. From coil post to gorund with the key on. See what you get.

o