usmc949803

cars been running pretty good. went to store this morning about 5 miles away. shopped for 15 mins went back out car wouldnt start. voltage dropped all the way down as car was trying to turn over. got a jump a few minutes later and started. as driving home noticed the volts were dropping. was at 8 or sop when i pulled in driveway. took off hood and got meter. alt voltage was 13.6 battery 13.6 witrh car still running. looked inside both volt gauges (in dash and after market) reading same. turned off car. wont start again. battery terminals clean

starter replaced a few months ago
alternator repalced with rebuilt ac delco two moths ago

usmc949803

voltage with key on right now 11.5 at battery and 11.5 at alternator

camaronewbie

I'd have battery tested - just because it has volts doesn't mean it has amps to crank.

usmc949803

just jumped car. started right up. checked voltage on battery and alternator and its dropping once jumper cables are off. so alternator? battery? both???? couldnt the battery go bad and mess up alternator like diode????

30 over

i have had related issues myself with the factory harness but ur running a setup like mine i see i have same engine and carb ;D to simplify things first check ground see if contact area is clean then from there if ur still having trouble check main starting harness from starter and work ur way back to see if u have loose connections and such i.e. fuseable link

usmc949803

i checked voltage at starter battery and alternator and it all the same. also when i jump it with another car it starts right up so if it had anything to do with starter or wiring with that it shouldnt start either way right? i have it running and the voltage out of alternator is 12.3 same as battery. when i press gas the voltage doesnt increase at all. i took jumper cables off. then tried to start car again and it did but overall voltage is around 12

usmc949803

just brought battery and alternator to be checked at different places. alternator showed bad voltage regulator. guy replaced it. battery showed 94a instead of 800. got new battetry. put in car. started right up. only thing is read voltage and showing 12.2 from large wire on alternator while car running....

usmc949803

both wire in plug that goes to alt (red and brown) with key on test light works.

usmc949803

if battery is good, alt is good, alt plug (red and brown wires) light test light has to be that ground wire or the red pos wire that goes to alt large stud and battery pos right?

took ground wire that goes from battery neg to engine and small wore that goes to body it looks fine any way to make sure? ohm test?

usmc949803

alt shop had me take my red jumper wire connect it from stud on alternator that has large red wire and connect other end of red jumper to battery red terminal. no change. so that would mean that wire from alt to battery is fine. i also checked with test light that wire on both sides of fusible link and it lights up. tried using the black jumper ends (only) from battery negative to body where i get ground and no change. so that would mean my ground wire from battery is fine.

has to be alternator still even with bench test correct???????

kd5icr

iTrader: (2)

Ok. Try taking the ground fron the body to the engine block. You should be able to find a place. I have seen it run to the top of the alt bracket. But no matter were you put it make damn sure that it is a clean spot all metal no paint no nothing just bare metal. Yes the wire that is on the back of the alt is the charge wire for the battery. Check it and make sure it is tight. You might even want to take the wire off and see if the stud itself is loose, if so make it tight and then replace the wire do not over thighten it you could strip it or bust it off. What do the cables look like? new? old? whats up with those?

NINÅ

usmc949803

havent driven car but started it and ran it fore a few minutes numerous times since yesterday and starts every time and voltage reads between 12.2 and 11.9 not running/running.

kd5icr

iTrader: (2)

11-12 That is to low. 13 volts in the norm. Double check the ground wires on the whole car, every one of them. make sure they are clean and tight.

usmc949803

got another alternator from shop put in and still same. just took my new battery up to advance auto and checked fine. brown wire going to alternator getting 11 volts or so. (Battery is around 11 volts now) Large wire from battery to starter new. put on extra ground between block and body. any ideas????

usmc949803

have mm hooked up to wire that leads out of alt to battery. watching will trying to start (with car jumped) volts drop from 12 to 5.5 and doesnt turn over

usmc949803

got car started. brought to advance auto for their charging/starting test. got the battery tested then test couldnt continue. said a dropo could cause test not to progress. went home took starter out and had it tested. 95 amps. said it isnt drawing power. battery was a little low but i knew that. so seems starter, battery and alternator tested fine. wire between battery and starter new. added another ground between block and body. nothing is changing the problem.....

NINÅ

usmc949803

voltage is between 12.3 and 11.8. it goes down as driving. as far as internal of alternator there were two different one installed from alt shop that bench tested putting out over 13.6 volts.

heres the wiring and all has been checked or replaced

Alternator
One wire from stud to battery positive
Plug with two wires:
Red wire goes to stud on alternator
Brown wire feeds in from firewall

Starter
Small stud
Purple wire from ignition
Large stud
Large wire from battery positive
Red wire to relay on passenger side firewall
Two red wires from driver side firewall

NINÅ

gsmarcano

good info guys thanks.

usmc949803

got alternator tested at another place (just to triple check) and its putting out 14.4

the battery only drains while running. when off volts stay same.

usmc949803

well had alternator checked five times at five different places. two fail three pass including alt shop again. figured wires are new and checked. battery and starter checked twice. got a used plug for alternator from shop and swapped it out and it works. ive got 14.7 volts 13 at idle. now keep in mind the plug was checked a few times over last two weeks and had voltage coming through it. no corrosion and not loose. no idea....

NINÅ

Nitewulf98

Did you ever get this problem fixed?

I am having similar problem in my voltage is very low, but mine is doing it at idle and goes up as I get on the throttle. The voltage gets so low that lights dim, turn signal slows down, and even will stall the vehicle (started 3 months ago). I have checked and cleaned all the grounds as well as the battery posts (which still had dielectric still between contact). Also, the problem is worse under load from cooling fan, heater on, or headlights. Although, there are times when all are on and I am sitting at 13V while idling. I thought it could be reverse problem in that my idle was killing the voltage and stalling the car, but tps, iac, maf, rpms, and fuel ratio are all good. I am going to look later this week for a short in the system, but are there any other ideas that I have yet to try?

BTW: 89 IROC TPI 350, all battery cables 1yr old, alternator is a powermaster 1 yr old, battery is OPTIMA red top 1 yr old. Problem is 2yrs old

NINÅ

camaronewbie

Yep - have the battery and the alternator tested - new doesn't mean good. 13v at idle is not enough (assuming the guage is accurate) - you should see closer to 15v at idle.

ASE doc

Check connections at starter. Fuse links at starter supply power to ign switch and lights. Be sure they are in good shape. Perform volt drop test across them with brights and fan on. Perform the same test on wire from batt- to block and small ground wire from batt- to body. Sounds like you have volt drop in wiring between batt/alt and ign, light circuit. 13 v is not that low at idle, especially with loads on. If you get 14+ above 1,500rpm, alt is probably not the issue.