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1982 720 Struggles to Start Every Time

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Left the headlights on for 15 minutes with the car not running about 4 months ago. Ever since, the vehicle struggles like this every time I start it, no matter whether cold or hot. Replaced the starter but that made no difference. What could likely be the culprit? Thanks for any advice 



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Leaving the headlights on for any amount of time shouldn't matter. 



I hope you kept your old starter as it's not likely the cause. You've just traded an original good quality starter for one of much less quality.


As you already changed the starter I'll assume the positive cable is on properly. Follow the negative cable to the intake and make sure it's clean and tight.


Use jumper cables from another vehicle and clamp to your battery cables. What happens? If the starting is improved then it would seem that the battery cable connections are poor or maybe the battery. Remove the battery cables and thoroughly clean them and the battery posts.


Place a meter across the battery posts and measure the voltage with the engine off and with it running. What do you get?



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Thanks both of you for your responses!


I'll try out the jumper cable suggestion, however when I put my multimeter to the battery while off it reads full (~12.7v) and when I hold multimeter to battery when I turn the key it barely dips (maybe drops to ~11 or ~10v but never below 10v) so I was curious as to whether this would be the battery as well. The battery cables have also been freshly replaced and are damn near new + clean looking; got replaced maybe 6 or so months ago.


Key was not on no, just the headlights then when I came back it struggled to start like the video above. Perhaps I should check the coil. Any advice on how to check if it's bad? If it just looks burnt?


Fuses got replaced recently too but perhaps the fusible links aren't all that nice. I'll double check those too


Thanks again for your help both of you

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2 hours ago, Stoffregen Motorsports said:

Did you leave the key on too? This can overheat the coil and/or the ballast resistor. A bad ballast resistor can cause hard starting as the ignition is not getting full voltage during cranking.


Another thing to check for is burned out fusible links.


After '78 all Nissans had EI ignitions and one of the safety features built in is that if there is no running signal the EI stands down. There is no current through the coil.  


Fusible links...

The starter is the only thing not protected by a fusible link. The starter is directly connected to the battery positive cable. As long as the fusible link directly connected to the ignition switch is good there is a start signal to the solenoid. Otherwise at this point fusible links don't really matter.



The ground is on the intake, so engine is directly grounded and though the transmission mounting bolts, so is the transmission the starter is bolted to. Body ground, at this point, doesn't really matter.


Cables may be new but the battery isn't. Check the posts and clamps again are wire brushed clean and because the ground cable was rep;laced chech where it bolts to the intake.



When you use jumper cables from a known good battery clamp the ground to the engine block. If this solves the problem, maybe the ground cable is bad. 


Booster cables will show the cables are a fault or the battery is weak. Don't run out and get another battery till you are sure the alternator is charging it properly and fully

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Thank you so much for the in-depth response. My understanding is that the squealing noise that comes immediately after the car turns over is from the alternator belt being a little loose. Could this signify that the alternator is not properly and fully charging the battery? If the belt doesn't matter, any good ways to ensure the alternator is indeed doing it's job?


Sounds like the list of things to check should be:

-> Check all battery cable connections and make sure they are thoroughly cleaned and well connected

-> Check the fusible link directly connected to the ignition switch (I'll probably need to search where this is at)

-> Test with a good battery to eliminate any wiring or cable issues as being the problem

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Alternator pulley slipping immediately after starting is not unusual, because you've just worn down the battery cranking the engine, and now the alternator is attempting to recharge the battery and puts a heavy load on the belt.  It does mean that the belt needs to be tightened or replaced.  I don't know about the 720 pulley, but some of the earlier Datsun V belt pulleys just aren't very good, either.

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I don't think your fusible links have anything to do with this issue.  You have weak starter cranking and that has nothing to do with any fusible links.  Either your battery is going bad/dead and not supplying sufficient current, or the wiring has an issue with high resistance limiting current carrying ability, which is generally a problem at a connection assuming wiring hasn't been messed with/changed.

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Sounds like the list of things to check should be:

-> Check all battery cable connections and make sure they are thoroughly cleaned and well connected.


As both battery cables were replaced, both ends of the ground cable must be checked including the connection to the intake manifold. If it was off, perhaps it wasn't properly put back on.


-> Check the fusible link directly connected to the ignition switch (I'll probably need to search where this is at)


As far as the working of the starter, if the starter engages then the signal from the ignition switch is fine and the fusible link to it must be also.


-> Test with a good battery to eliminate any wiring or cable issues as being the problem.


Jumper cables to the battery cables. If there is no change move the ground jumper cable to the engine block and try again. This should now work and proves that the ground cable isn't working properly.


If the starter now works properly, then the battery is at fault OR it is not being fully charged. With the engine running a volt meter across the battery terminals should read around 14.4v.



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newer battery cable use the thin round type connections. I have seen cracks in both thinking you got it clamped up good but its really loose.


to check batter connection just get a Volt meter and measure from the battery post to the battery cable right at the spots(with key ON). if you get like 2volts then you have a voltage drop between the 2 as they should be none. as its a shorted together.  most times cleaning this will slove this . then do the neg cable and then to ground.


also if it gets of of time on the dist it can be hard on battery also.

But usually soemtimes a old battery is now weak after the lights being on. 


I had a Red Optima battery and after 2 lights on incidents battery was junk.



I have something similar to this in my car and I watch it while driving and using the lights , heater ect.  I can tell if the alternator is loading down or not. If loading down then battery will be weak for the next day start.

Example I had a Z Car. driving in daytime was fine and night coming home from 2nd shift in cold dark and rainey day the battery was actually draining when I got home and not enough to start the next day. if you got lights wipers and heater fan ON and its reading 12.5 volts you alternator isnt working esp at 2000 rpms

Edited by banzai510(hainz)
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Anything under 13.7V or so (13.5 at the lowest) with fans and headlights on I would consider an undercharging alternator.  Anything about 15.2V or higher I would consider an overcharging alternator.  Either way, you are looking at rebuild or replace, should you find your alternator is outside of that range.

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1 hour ago, Stoffregen Motorsports said:

I was thinking a possible fusible link, in anticipation of a charging system that isn't functioning.


Duh, I forgot the electronic ignition... Thanks for clarifying.


I knew that you knew

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