Datsun (Nissan) 1980 280zx electrical problems

Looking for a fix for the following symptoms. (may be separate and/or associated problems)

Summary: 1) much longer than normal warm starting. 2) normal cold starting. 3) “Chatering” of electrical box at passenger right fuse box area. 3) Total shutdown of electrical at cruise (65mph) including lights and engine, followed by sudden backfire, and then everything back to normal.

So, let me take you through a normal day.

Cold engine. Normal start. My plans are to go from A to Z, with all the normal stops. For months, all is normal. But some days, when it is hot, after several stops, and the engine is at the normal operating temp., when I try to start, the starter engagement requires a long time (instead of a few seconds, it might be as much as 15sec’s for the engine to finally run) Sometimes when this happens, the “chattering” occurs.

I can deal with this problem, but having the electrical system total shutting down at interstate speeds, is really unsafe.

The uncomforting part to this whole story is that I can go for weeks of going to work without any problems. Then suddenly, at 65mph on the Interstate Highway, the cars electrical system shuts down just for a moment,just long enough for me cuss the unthinkable, and then everthing is normal again.

Hope you can help…

You may have two problems here. The starter “chatter” could be either dirty battery cable ends or a failing starter.

The part about a total electrical shutdown could be any one of several things. The intial suspect in my opinion would be a possible fault with a fusible link wire end connector followed by an ignition switch fault
There should be a box under the hood, passenger side, with fuses, etc. and fusible links. With age the fusible link ends burn or corrode and a bad connection can lead to problems like this.

I’ve seen this several times on Z-cars, including one belonging to a guy who I stopped to help when I saw him broke down. He said his car had been in the shop repeated times in the past year for problems like yours and had 2 battery replacements, 3 alternators, 2 starters, new battery cables, and yet there he was sitting on the side of the road after all of that wild guessing.
The problem was the lightweight link wire end, pure and simple. About a 3 minute fix on the side of the road and his problems were solved.

Not saying that IS the problem; only that it would be the first thing I would look at and since there are several links they should all be closely inspected since everything electrical on the car goes through; except for the starter motor current draw. Hope that helps.

The chattering in that relay/fuse box is probably caused by the voltage dropping too low to keep the relays energized. The voltage can drop anywhere between the battery/alternator and the circuits they power. Poor power connections, or poor ground connections, can cause voltage drops. Check the voltage, beginning at the battery. work your way through the power distribution center, to the dash. Check the power wire(s) to the alternator. Make sure the nut (or, bolt) is snug and the terminal isn’t near-touching the body of the alternator. You, or your electrician, need to follow the power distribution circuits. Hello, wiring diagrams.

Look for a small, black, plastic box in front of the battery. It will contain up to six fusible links. The fusible links are different colors (amperage), and look like loops of wire with a terminal on each end. Pull them out and examine them. Use an ohm meter, and while flexing the fusible link, watch the ohm reading. The ohm value should stay at zero (no resistance).

I’m not sure what electrical box you are refering to. The fuse panel or a relay possibly. Whatever it is, I would suggest looking at and check the connections to it for a problem.

Since all the electrical systems seem to fail when the power problem occurs then this means the trouble is either in the main accessory power area or possibly, the ignition switch wiring if it controls the lights also. I like the suggestion of checking the fusible link connections as this is a real probability. You may be able to locate the problem area by tapping lightly on suspected trouble areas with a screwdriver handle.

This car also uses a fusible link between the alternator and battery so it’s possible that the starter chatter could be due to an intermittent weak battery caused by a fusible link end connection coming and going, which could be allowing the battery to sometimes fail to be fully charged.