I need help with a electrical issue on my 1976 Datsun 280z

[76280z]

yesterday i got a 280z . today I started digging in to it and I realized I was not getting any spark. I tested the coil which nothing happed, so I took the coil out of my 280zx and just tested if it was just an issue with the old coil  but even with the new coil their was nothing. I took the distributor cap off and cleaned all of the contacts and was still getting  no spark. and just to see if something was up I reconnected everything and sprayed starting fluid in the manifold and it fired up for a second then died i went to spray a little more in and their was no more spark. Anyone know what the issue could be ?

Update I cleaned up all of the connections and Their is no signal coming off the distributor to the coil. does anyone know what would be causing this ? 

Edited December 15, 2020 by 76280z

[dutchzcarguy]

Get yourself a service manual (download) as there can be a million issues with the electric system and walk through the complete system..  Get al the contacts clean and at one point you'll see a very bad contact, that was the culprit. just go through the whole system.. it needs a clean anyway after all these years.

[Racer X]

6 hours ago, 76280z said:

 Anyone know what the issue could be ?

Sounds like you don't have any spark.

😉

Seriously, check the ballast resistor with a ohmmeter. They burn out eventually, and then the condition you describe happens. The car rides up, then after starting, it dies.

The ballast resistor is bypassed for starting, then after the cranking is done power is directed through the resistor to reduce the voltage going to the coil.

 

 

[SteveJ]

12 minutes ago, Racer X said:

Sounds like you don't have any spark.

😉

Seriously, check the ballast resistor with a ohmmeter. They burn out eventually, and then the condition you describe happens. The car rides up, then after starting, it dies.

The ballast resistor is bypassed for starting, then after the cranking is done power is directed through the resistor to reduce the voltage going to the coil.

 

 

 

6 hours ago, 76280z said:

yesterday i got a 280z . today I started digging in to it and I realized I was not getting any spark. I tested the coil which nothing happed, so I took the coil out of my 280zx and just tested if it was just an issue with the old coil  but even with the new coil their was nothing. I took the distributor cap off and cleaned all of the contacts and was still getting  no spark. and just to see if something was up I reconnected everything and sprayed starting fluid in the manifold and it fired up for a second then died i went to spray a little more in and their was no more spark. Anyone know what the issue could be ?

If it started with starting fluid and died, you probably have more than one problem.

1. You have a problem with the ballast resistor or the ignition switch. You have spark when the key is in start. Otherwise the car wouldn't start on the starting fluid. When you release the key, a bad switch causes you to lose spark, or a fault in the circuit is causing you to lose voltage at the coil (sometimes the ballast resistor). Also it could be that you are using up the starting fluid you sprayed in (See #2).
2. It doesn't sound like the injectors are firing, so you don't have fuel. That could also (in part) be from a bad ignition switch.

As suggested, download the FSM and the wiring diagram. Get started with a voltmeter. If you don't know how to use a voltmeter or read a wiring diagram, then find a friend who knows how to do so.

[Dave WM]

welcome to the world of old cars. You will become a old school mechanic, prob a better one than a modern era mechanic that works on modern era cars, if you keep the car. There is no OBD, so you have to learn the old school way, using your eyes, ears, nose, brain, and the FSM. A few simple tools like a VOM (DMM today), a test light, will go a long way.

The upside is these cars are VERY simple when compared to modern OBD cars, the down side is just about every system can be suspect since you are dealing with not only 40+ year old wiring and parts, but also prior owner hacks. Still the basics apply, compression, fuel, air, spark, timing. Get those right and it will run, has too.

You should start compression, a base line reading just so you can scratch that off the list. Next spark order, again easy stuff, prob not the issue, but check off the list.

fuel, get a pressure gauge and read the FSM

air, new air filter, smoke out the system to find vacuum leaks, make sure the throttle is opening, easy stuff

Spark, start with some new NGK plugs, verify they actual spark by pulling one, lay it on the valve cover and crank the engine.

Injectors working, you can listen for them clicking with a stethoscope or even just a long screw driver on the injector and listen to the other end. They could be clogged so look at the new spark plugs see if they are getting wet with fuel.

common issues NOT addressed in the FSM, faulty intermittent start switch, bad grounds, corroded wires. So look into those as well. there are YouTube videos on how to check start switch.

 

 

 

 

Edited December 14, 2020 by Dave WM

[Dave WM]

what you don't want to do is just start replacing stuff, plugs ok since they become dirty and hard to read (more about that after you get it running). everything else should be tested per the FSM. As parts get replaced, the likelihood of an error in the replacement creep up, Often its a single point of failure that keeps the car from starting. Now once its running it may run poorly and other things can be wrong, but again you want to test 1st, if there is a defect check the replacement before installing, then see if there is an improvement. The issue with these cars is the fuel injection is open loop by design, so any defective part can mess up the fuel mix, the ECU can not learn or detect any problems, there is no limp mode etc... it just fires injectors based on limited input parameters, mostly coolant temp and throttle position (idle mid range, high range) and rpm. No O2 feed back to monitor the fuel air mix, that is where reading the plugs comes into play.

Once its fully sorted the system works very well, Your main issues typically will be corroded/broken wires and bad grounds. This is were a visual inspection is a must.

Edited December 14, 2020 by Dave WM

[Pilgrim]

Always look for the simplest thing that can cause the problem. Problems like this are very seldom due to complex factors.

Ballast resistor? Good idea.

Dirty contacts? You bet.

And so on.

[Zed Head]

12 hours ago, 76280z said:

yesterday i got a 280z .

sprayed starting fluid in the manifold and it fired up for a second then died

He's probably hooning around the neighborhood.  Maybe it was just out of gas.  Looks like it had spark all along.

[76280z]

the car was sitting for 12 years and the second time i sprayed starting fluid in nothing happened. 

[Zed Head]

18 minutes ago, 76280z said:

the car was sitting for 12 years and the second time i sprayed starting fluid in nothing happened. 

What did you do to the engine and car, gas tank, fuel lines, fuel pump, injector system, etc.,  before you tried to start it?  I had an engine once that only sat for a year and it wouldn't start until we put oil in the cylinders.  The rings get dry and there's poor compression.  Plus your injectors might be full of bad fuel, even water.  12 years is a long time.

[76280z]

 

12 hours ago, SteveJ said:

 

If it started with starting fluid and died, you probably have more than one problem.

1. You have a problem with the ballast resistor or the ignition switch. You have spark when the key is in start. Otherwise the car wouldn't start on the starting fluid. When you release the key, a bad switch causes you to lose spark, or a fault in the circuit is causing you to lose voltage at the coil (sometimes the ballast resistor). Also it could be that you are using up the starting fluid you sprayed in (See #2).
2. It doesn't sound like the injectors are firing, so you don't have fuel. That could also (in part) be from a bad ignition switch.

As suggested, download the FSM and the wiring diagram. Get started with a voltmeter. If you don't know how to use a voltmeter or read a wiring diagram, then find a friend who knows how to do so.

I cleaned everything up and still no spark but when i was testing the connections their is no signal coming off the distributor 

[Zed Head]

1 hour ago, 76280z said:

 

I cleaned everything up and still no spark but when i was testing the connections their is no signal coming off the distributor 

What do you mean by signal?

Are you using a meter?  You really need a meter to work on these cars.

And, if you don't answer the questions people can't offer specific advice.