charging issues

[TooFoxy]

my car will not charge battery after its running... will run for a few mins and when batt is dead voltage drops and car stalls....
alt and the alt regulator are good... all of the fuse links have continuity when they are removed from starter silinoid..the pigtails arnt burnt good connections just when running car only see's 12.5 volts when u rev it still stays at 12.5..... any ideas?.... its an 88 w/ stock alt setup.

 

[jrichker]

Have you checked the grounds? The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.

 

[Repostyle]

Could the battery be bad and just not take a charge anymore? How old is the battery?

I've had battery problems in the past, clean your connections and make sure they're tight to the battery.

Most battery/electrical shops can test your system and make sure everything is working like it should. But like I said, my guesses are battery or connections.

 

[HISSIN50]

How did you ascertain the alternator is good?

I agree - take your battery in for a check. A bad cell can impede charging.

Good luck.

 

[TooFoxy]

battery is semi new and i had it recharged yesterday no problems it test at like 600CCA i took the alt off and took it to the store had it tested the old one was bad and it had lifetime warrenty so i have a brand new alt now too... still i get no voltage.. if i turn on lights or heater.... it drops to like 10.4 volts if i rev it dosnt budge stays at 10.5 volts and i am not using stock gadge using a volt meter. grounds are tight

 

[jrichker]

Look for voltage on the exciter wire - Lt green/red wire - it should read 12 volts.

Look for 12 volts on the yellow/white wire.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-90 wiring

http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

 

[tjm73]

A friend had a similar problem. Is battery was good and the alt was good. But it would not run for very long. Turns out his battery cables were bad. The newest Fox is 13 years old now. Items like this are gonna start going bad and they are easy to forget about.

 

[webshot]

Funny thing kept happening to my buddy when he was replacing his voltage regulator. But it is recommended that you screw it into the firewall before placing the connector in. Could be an old wives tail but he went thru like 3 brand new ones day then soon as he installed the other way around (screwing it into the firewall first) it worked fine. Some old school mechanic told us that.

 

[jrichker]

Funny thing kept happening to my buddy when he was replacing his voltage regulator. But it is recommended that you screw it into the firewall before placing the connector in. Could be an old wives tail but he went thru like 3 brand new ones day then soon as he installed the other way around (screwing it into the firewall first) it worked fine. Some old school mechanic told us that.

All Mustangs since 86 have a voltage regulator built into the alternator. They do not have an extrnal regulator like older cars.

 

[TooFoxy]

UPDATE: took alt to diffrent store and guy tested it bad.. becuase it had warrenty i took it back to original place and told him a 2nd store tested it bad to try retest it after he did it wasnt putting out (diffrent guy than first test) so maybe guy there was just a dumb*** now i got the new alt in... and when it idles 12.5volts... rev it up to about 3,000rpms and i get 14.5 comes down to idle.... still 14.5volts i thought it was crappy but my guage in car stuck up real high reading like 16volts and wouldnt come down so i checked w/ volt meter and sure enough it does stick right about 14.5- 14.8..... isnt that bad? shouldnt it return to like 12.5 at idle after u rev it?

 

[HISSIN50]

14.8 volts is great IMHO (though it is the upper eschelon of what I would want to see).

It also might drop after the battery is topped off and you have driven it some (in case the battery is a bit discharged right now from workin on it).

 

[webshot]

All Mustangs since 86 have a voltage regulator built into the alternator. They do not have an extrnal regulator like older cars.

oooops my bad, I dont know why, but I must have been thinking of my recently departed 85,,,,Glad you got it tho dude. If you ever get a 85 or lower bolt the VR down first.....:thumb:

 

[1SLO306]

All Mustangs since 86 have a voltage regulator built into the alternator. They do not have an extrnal regulator like older cars.

my car is an 89 and my alt has the regulator mounted on the back of my alt.

 

[HISSIN50]

my car is an 89 and my alt has the regulator mounted on the back of my alt.

Is it the stock 2G? Got some pics?

 

[1SLO306]

i dont have any pics of the alt. but i know the regulator mounts right on the back of it. ive had to replace it about 2 months ago.