No start Conundrum

1980-1986 Datsun 720 forums. All 720-specific topics and discussion can be found here.
86 720
Posts: 199
Joined: Tue Sep 29, 2009 11:55 am
Car: 1986 720 4cyl Standard Cab

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Kind of an odd situation...

Was driving home from work today when the radio(aftermarket) quit, and my turn signals remained solid, as in not blinking. The battery light never came on either.

No other problem, no hesitation or lurches, etc...

Got home, and pulled all the fuses and they all checked out ok. Went to start the truck and it wouldn't even turn over, as in the starter wouldn't turn. Turned the key to acc and the radio came back on. Gave it a few more tries, and it still wouldn't turn over. All the electrical works, headlights, cab light, etc.

Went inside to think about the problem, got some dinner, and headed back out. Turn the key and voila, it started! Let it run for a few minutes, and shut it off followed by a attempt to start again 5 minutes later. Again, no start. Played around with it a little and noticed the radio would intermitantly work, but it still won't start.

I think I have an electrical issue, and came back inside to think about what might be wrong. Any ideas?


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PEZi
Posts: 21113
Joined: Thu Dec 11, 2008 8:21 am
Car: Mitsubishi Lancer Evolution IX Mitsubishi Racing Edition
Location: Pikes Peak, CO
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wow... i hate electrical issues... this is actually confusing the hell out of me right now

86 720
Posts: 199
Joined: Tue Sep 29, 2009 11:55 am
Car: 1986 720 4cyl Standard Cab

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Me too!

I just went outside, and it started right up... But one I turned it off, it went back to its no-start problem...

I've taken it to Autozone and had the battery, starter and alternator tested a few times and they all passed.

I do remember the previous owner stating the battery was not the one listed for the truck, and you can tell because the posts are positioned wrongly. If it were the battery though, you'd think I would have had a problem before now.

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breadbox
Posts: 8550
Joined: Tue Oct 17, 2006 4:09 pm
Car: Red 89 240sx,Black 89 Koop, White 84 720 4x4KC
Location: Va Bch

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ignition maybe? try to bypass it and see if it starts. Some guy with a 240 had weird electrical problems and replaced that finally and everything was fine oddly enough.

GahannaKid
Posts: 40
Joined: Mon Oct 05, 2009 9:57 am

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I had a similar problem with my SuperCoupe awhile back. Turns out the starter was getting too hot after a few minutes of running. Replaced that & my problems went away.

86 720
Posts: 199
Joined: Tue Sep 29, 2009 11:55 am
Car: 1986 720 4cyl Standard Cab

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Turns out it was a bad battery, as in not even the right battery for the car.

Looks like the previous owner just put in a lame battery so it would start and take off, probably surprised it would last this long.

Replaced all the fuses with new anyway. I did notice the negative cable is corroded, will replace that this weekend with new cable. Also noticed the ground cable from the batt. neg. to the battery tray(body ground) was loped off and taped. Will replace that with new this weekend too.

86 720
Posts: 199
Joined: Tue Sep 29, 2009 11:55 am
Car: 1986 720 4cyl Standard Cab

Post

Update:

Not only was it a bad battery, but also a bad alternator.

Truck did the same thing coming home from work on Thursday night. Stereo went dead, and the turn signals froze. So when I arrived home, I removed the pos. battery clamp and she automatically died.

Removed the alternator yesterday and brought it down to Autozone to have it tested, failed three times, new alternator!

The alt. # Autozone has for this year and engine is wrong. The electrical connection is much larger. My alt. had a smaller "T" shaped connection.http://www.autozone.com/autozo...mport

Also replaced all the battery cables with new 2 ga. cables. The positive cable ended up being 32" long,(25" was just a little too short, and 32" is just a little long) but I'd rather have it a little long than short. The negative cable is 25". I also noticed the stock body ground was missing too! Someone at some point had cut the posts off both the battery connection and taped the engine connection and tucked the wires. So when you look in, it looks like they are connected. I removed the tape and reattached the engine connection, so at least that was grounded. It's amazing how much brighter lighting is when there is a good ground connection!

So far she is running like a top!


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