Runs at about 9v at idle and about 14v at freeway speeds. Alternator was changed recently... everything else is suspect. Ideas?
raise your idle or swap a pully size to speed up the alternator, at what RPM does it start showing over 12V?
Much higher than a fast idle. My Tach flips out because of the low voltage so it reads crazy at idle.
Could either be the battery is about shot, or the alternator or generator can't keep up with all the accessories unless the engine is revved up constantly, or the wiring is insufficient. If you have a 30 amp generator feeding 70 amps worth of accessories, then the problem is your underpowered generator can't keep up. If you have a large alternator and you don't think you're exceeding its capacity at idle, then it sounds like maybe a wiring problem. If you have a bunch of power accessories like electric fans, electric fuel pumps etc., running off of your fuse panel, and the voltage gauge is hooked up to the fuse panel, and you have way too thin of a wire between the battery and the fuse panel, that wire will run very hot and give a "voltage drop" at the fuse panel while all those accessories are running. Try putting a voltmeter directly on the plus and minus terminals of your battery and check the voltage with the car not running. It should say something like 12.6 volts. Then try it with the engine idling. If it still says 12.6 volts, but your dash gauge says 9 volts, then I think the problem is probably weak undersized wires running from the battery to the fuse panel or weak connections at crimp terminals. Feel the connectors and wiring with your fingers. If they're hot or the connections feel crispy or burned, something's loose, or the wire is too small of a gauge. The wire between the generator or alternator has to be of sufficient size too because when your engine is running, all of the accessories are running off of the generator or alternator.
9v is kinda low for the battery with only the ignition to support. If it's running 14v going down the road, it shouldn't drop to 9 at a stop light. A healthy battery will maintain more on it's own. Test that battery IMO. Good Luck
I should add that some of the wiring from the battery to the fuse panel usually runs through the ignition switch and sometimes detours over to the headlight switch or a junction block or power distribution block. Most fuse panels have a direct line from the battery for things like cigarette lighter or dome light, but then separate inputs for "acc" and "run" come from the ignition switch to feed all the "switched" power things. Your dash voltage gauge is most likely tied into a "switched" power section of the fuse panel.
Thanks for the info everyone. I think my first thing is the Battery. The car is very simple electrically. Headlights, Tailights, front signals, eletrical fan & fuel pump, starter. It does have a full set (6) gauges. Other than that, not much else, no radio, wipers etc. It does have a one-wire GM alt... it think 65 amp. that was recently replaced. I'm going to try some of the ideas you guys had on saturday and let ya know. I'm not too thrilled with the wiring on this and I may just decide to rip it all out and put in a new harness. The guy kind of mickey moused it.
You do know that you have to rev the car up to about 2200 - 2500 RPM to get the one wire alternator to start charging, I hope. If you're checking the voltage at idle without exciting the alternator you will see a lower voltage, although 9 volts does sound like the battery isn't too good.
charge the Battery fully, then recheck volt meter reading. any alternator output to a battery that is not fully charged will be screwed up. one wire alternators are notorius for low volt output at idle. bigger pulley will help some but probably not enough
not always true-My 1 wire started charging at around 100 r.p.m.-which was too early for me (it is a 150 amp delco deisel unit adapted to fit my car) so I switched to a 4 1/2 inch Moroso pulley. problem...yo' batray is ded.
I agree with Max here. If the battery is low, the internal regulator should be putting out more, but without seeing the pully set up it's a tough call. It's a cheap part and an easy change. If it was a wire size situation, you should really be cooking it with 14v Flatman
You're going to need two wristwatch's to tell what time it is. Stick a voltmeter on the battery you can watch, run the vehicle around watch the dash voltmeter, is the problem on the whole circuit or just the dash? See how the meters agree.
on the fan...I haven't seen one that would pull down the voltmeter...the amps would certianly drop out, but the voltage would remain constant. in the grand scheme of the "K.I.S.S." theory of electronics, I still say load test the battery. (every time I type battery, I think of the Eddie Murphy "Talking Car"routine..."Saay Man..Somebody done stole your Batray. I say we go get the muthafucka." -sorry. had to share.) I am still curious what the amperage of the new alternator is...
Ok thought I'd give you an update. Checked the car out on Sunday. Everything seemed ok with the Voltmeter and I double checked the alt and the bat with a VOM... still good. Did a load test on the Bat and it's just barely into the yellow range. Get this, the voltmeter was reading Normal. Both at idle and at crusie speed. Everything seems to be working as it should. The Electric fan is out but its been like that for a while and temp has been ok. I know there's an issue with the wiring for the fan. Couldn't really drive it much on Sunday but today I drove it to work. Everything was fine. Idles at just before 12v and hits about 14.5v at cruise. Idle is about 1200. and the guages are all working fine. WTF??? I'm guessing it must be a wiring issue. Thanks for all the help guys. Rick
Intermittent problems are the worst. When you have time to troubleshoot them, they vanish. When your 100 miles from home, they come back. Good luck.
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