720 Electrical question

[fastboatman29212]

Does a coil go bad all at once, or does it start to show signs of failure gradually? My truck started acting up today. It would just shut off, (for like 1 second) and then start again like nothing was wrong. It happened tonight on the way home from work while I was doing about 50mph. Alternator light came on. As I put my blinker on and then began to pull off the side of the road, suddenly she started running again like nothing was wrong. I did a quick scan under the hood once I was home but nothing looks fried or disconnected.

Where do I start looking if it does it again?

[nissangirl74]

First thing I would do is get the alternator tested.
I checked prices online for the alternator and coil.
At Autozone - Alternator is $69 with a $17 core charge and a coil is $35.
If you had an extra $100 that you could afford to spend, and you find out that the alternator is shot or going South, I would get both of those and drive worry free.
Good luck! Hope this helps.

[fastboatman29212]

I know it's NOT the alternator. It's less than a year old. Besides, that would not cause the engine to just shut off. I am suddenly losing either spark or fuel. I could have a fuel pump going bad (electrical short) but I hear the pump run when I turn the key. Whatever it is, I hope I find it before it leaves me stranded.

[Davezilla]

Check and clean your alternator's electrical connections just to be on the safe side... loose or dirty connections can lose electrical contact and cause problems like intermittent failures which can be hard to troubleshoot.

For the coils, check and clean their electrical connections as well. Coils do tend to fail instantly but the next time you turn your key the engine will fire right up but will continue to die like that until they leave ya stranded so if your coils are original or you know they're going bad, change them out. Ignition modules *can* fail the same way where they fail but the engine may or may not start back up.

Most important would be to check and clean all electrical connections before buying anything to make sure you're replacing the right parts.

[fastboatman29212]

I think I found it. I had 2 bare wires under the dash that I think were shorting out the dash, radio and possibly the ECU, thus no engine spark until it reset itself. I think it makes the most sense of all the options.

These trucks will run with a dead or disconnected alternator as long as the battery has enough juice to keep the essential electricals running like the fuel pump.

I recently had my water pump go bad and the belt was not spinning the alternator. It still ran fine for 20 miles until I got home. I was running on pure battery.

Anyway, the bare wires have been properly insulated and she has not been acting up anymore.

[Davezilla]

That could very well be your problem... bare wires shorting to ground or to each other can cause all kinds of problems. I know how bullet proof these older Nissans are since my first one was a '79 280zx and I put that car thru the ringer and back... One thing I find very similar with this truck I just got is these cars are about the easiest things out there to work on as well.
Glad to see you're up and running again