Guest tankeater84 Posted April 20, 2005 Share Posted April 20, 2005 Ok heres the low down on the car. 81 280 zx Gl ive had it for a year and replaced several parts. New Alternator, Starter, Coil, Cap and Rotor, Plugs ( bosch +4's) and an optima red top. The Problem. One she won't hold a charge Two when running my voltmeter spikes out to 18volts Three while spiking all lights in the car fluxuate Four the idle is ragged while running and sounds like she wants to die on me Now heres the mind bender when i step on the brakes everything drops back to normal. I started having these problems 7 months ago right before i left on westpac with the navy. I haven't started her up to se what happens ( im a little nervous to do so) Can any one help? Id really love to get her running again before i start my motor swap next year V/r Morgan Quote Link to comment Share on other sites More sharing options...
4everDATSUN Posted April 20, 2005 Share Posted April 20, 2005 sounds like a regulator, which it doesnt seem you have replaced yet. often this piece fails in z cars. its the black box mouted on the fender by the alternator. you should search the forum and look for alternator upgrades. i think an 80's maxima/300zx alternator is best, internally regulated. on a second note, those bocsh plugs you have are a waste of money, any NGK would work just as good if not better. Quote Link to comment Share on other sites More sharing options...
Jolane Posted April 20, 2005 Share Posted April 20, 2005 I am thinking that your problem might be a short in the electrical system. To narrow it down, it sounds like it could be in the brake light electrical. I wish I had specifics, but this is where I would start looking. Joshua Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 20, 2005 Share Posted April 20, 2005 The Problem(s). 1) Won't hold a charge 2) When running my voltmeter spikes out to 18volts 3) When spiking all lights in the car fluxuate 4) The idle is ragged while running and sounds like she wants to die on me 5) (Now heres the mind bender) When I step on the brakes everything drops back to normal. FIRST AND FOREMOST: Get a REAL voltmeter, hook it to your battery leads, and see what is REALLY happening! Use a good digital unit. Fluctuating lights in MY mind at least means you have a diode or two going bad in your Alternator, and this will KILL your ECU in short order! SECOND: The brake pedal thing may be indicative of a DIRTY GROUND POINT ON THE DASH CLUSTER! When the common ground point gets dirty or corroded, the dash starts doing stupid things in a ZX, amongst them voltage meters that read wrong, dash lights that come on and off randomly, spurious "check light" malfunctions, etc etc etc. I am no S130 guy by any stretch of the imagination, but from friends' cars and their maladies, I would say to VERIFY what you have first, THEN move on with replacement of components. What I am getting at is the Alternator will KILL other components, so you need to check what it is doing INDEPENDENTLY from what the gauges in the car are telling you. I believe the 81's have INTERNAL Voltage Regulators in the alternators, so that will be a simple fix if you ARE seeing 18V at the battery (and if you've killed the batt a few times this is a good bet)---replace the alternator. If you see the gauge on the meter flicker, move around erratically, or pulse chances are the Diode packs are bad, and you need the alternator also. Remember that the surest way to KILL an alternator is trying to make it charge a dead battery! Once you have the alternator dialed in and working correctly, check everything again to see what it is doing when it gets a GOOD voltage stream to it. Some problems may dissapear altogether, some new ones may appear... (not what you wanted to hear, right?) But sitting for the duration of a WestPac indeed IS enough time to get corrosion buildup on terminals and connections that will cause a problem. The best advice I can give ANYONE regarding an older Z (and especially ones that have electronics in them) is to buy several cans of DEOXIT, and some Dielectric Grease, and GO TO TOWN on all your dashboard and critical connectors! You will be amazed how much better everything works after such a cleaning, and if you Dielectric Grease all the connections upon reassembly, you will be amazed how long they STAY clean! Good Luck, man... I don't envy the task ahead of you! Quote Link to comment Share on other sites More sharing options...
ecp48 Posted April 20, 2005 Share Posted April 20, 2005 All Zs and ZXs after, I believe 1977, do not have external regulators. It appears, as Tony D stated, that you may have a bad alternator. Pull it and take it to AutoZone, Advance Auto Parts or Pep Boys and they will check it without cost. Quote Link to comment Share on other sites More sharing options...
4everDATSUN Posted April 20, 2005 Share Posted April 20, 2005 my bad didnt pay attention to the year and model, def look into replacing that alt. Quote Link to comment Share on other sites More sharing options...
Guest tankeater84 Posted April 21, 2005 Share Posted April 21, 2005 Thank you very much everyone. since im getting ready to replace all of my gauges any way ( oh the joys of recalibrating a speedometer) i will pick up some diaelectric grease and clean and treat all of my connectors while im at it. now as for the alternator this will be the 3rd one if i need to replace it again so i might just have a bad lead to the voltage regulator. I will check it out after i get the prognosis on the current alternator. wish me luck folks cause im gonna need it. Quote Link to comment Share on other sites More sharing options...
4everDATSUN Posted April 21, 2005 Share Posted April 21, 2005 pick yourself up a multimeter, its def worth it if you plan on doin all the work on your car by yourself. that and a test light. you will use it all the time, i do. make sure your getting the right voltage at the battery, and all that stuff. check resistance of main wires. saves alot of time then guessing. good luck Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 21, 2005 Share Posted April 21, 2005 Thank you very much everyone. since im getting ready to replace all of my gauges any way ( oh the joys of recalibrating a speedometer) i will pick up some diaelectric grease and clean and treat all of my connectors while im at it. now as for the alternator this will be the 3rd one if i need to replace it again so i might just have a bad lead to the voltage regulator. [/u'] I will check it out after i get the prognosis on the current alternator. wish me luck folks cause im gonna need it. I second the suggestion to get the multimeter! You are onto something with the voltage sensing wire from the battery to the alternator's regulator! If there is corrosion, you will run all sorts of screwy voltages! Grounds do the same thing. I added ONE 14 Gauge wire from the external regulator on my 75, to the ground point on the fender well. Before I ran this ONE wire, the voltage was all over the place, upwards of 15 VDC! After the ground wire was in place, the voltage went to 13.8VDC at idle, and in NO case would it go above 14.5 VDC even with all the accssories running (including the 100W H4 lights up front!) If the grounds for the accessories are gone, it gives spurious indications, and if that feedback line is corroded, or bad in any way TO the alternator, It will CRANK out the voltage till it SEES 13.8V back to it on that line. There is supposed to be less than 1VDC difference between what is at the battery, and what is at the alternator feedback line to the alternator (at the alternator). If that is not the case, fix IT first, or most likely you will waste another Alternator (though AZ and many of the mass merchandisers are not that great at providing properly rebuilt parts like Datsun Alternators!) And remember, always CHARGE your battery before you run it up to do a charging system check. Nothing kills the diode pack faster than overamperage from trying to fast-charge a battery. The windings will hold it, but the diodes will literally melt the solder off the end trying to keep up with the ampreage requirements! Quote Link to comment Share on other sites More sharing options...
Guest tankeater84 Posted April 23, 2005 Share Posted April 23, 2005 Hey yall got it licked in one. i gave up on chasing it through the system ( lack of time and patience) so i yielded to the repair shop on aero drive in san diego (Zwhizz) and the found a burnt out Fuzeable link running to the voltage regulator that had shorted out and was causing the alternator to max out in an attempt to read 13.5 volts back to it hence forth the power surges to the lights still not sure why pressing the brake dropped the voltage down to normal but hey shes running fine now and i will have pre mod photos up soon. once again thank you all for your advice and help. V/r Morgan Quote Link to comment Share on other sites More sharing options...
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