got my 88 GT today..alternator question

DA-MAX

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Dec 15, 2004
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anyways I got my 88 GT today, I love it(came with intake, MAC headers, H-pipe and tail pipe, UDPs). :hail2: the 5.0

anyays the car developed an idling issue today...so first I checked the battery voltage and it would not go over 12.5-.6v while idling, would steadily drop as the car sat(only rose when pressing the gas), when the a/c is tunred on the car basically dies...so that led me to think alternator is bad...I did a search on here and found that many times using UDPs and the weak 75amp stock alternator don't make a good combo. so this led me to get a new alternator with a stock pulley. I got a new alternator, and instead of using the alt underdrive puley, I used the stock alt pulley(also got the new correct belt size). so now I'm running stock alt pulley, ud crank pulley, ud wp pulley and stock ac pulley and STILL the alternator WON'T recharge the battery(slowly dies) and the car's idle surges and fluctutes.

I searched again and found some more info and was wondering:
1. should I just go back to all stock crank and WP pullies??
2. is there a fuse or a fusinle link that could be blown between the alternator and battery??

any help would be great, I can't wait to get this car fully running!
 
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you *might* be on to something. There's a black/orange 10ga wire that runs from the alt. to a 14ga green fuisible link...it merges w/ another wire at the fusible link, I believe. Check the black/orange wire and inspect the fusible link. You should be able to buy fusible links and normal wire at autozone in the electrical section.

If the wires pass a visual inspection, I'd unhook/unplug them from anything they're hooked up to (not necessarily remove from the car, just unhook from components) and use a digital multimeter to ohm out the wires and see if you have a bad spot.

With a new alt and a good battery, it almost has to be the wiring; new products can be faulty, but since the old and new one had the same issue...

Good Luck :nice:
 
Do a 3g 130 amp swap :nice: its easy only took me a hour to 2 hours to do it and i think it only cost me less then $100 bucks to do it (junk yard alt.). Once you do it, you can have your A.C/Heat on, with windsheld whippers going along with a system and wont have any dimming going on :nice: . The stock 75amp just doenst count it. I still dont understand why Ford had to put that alt. in the car :shrug:
 
So what are voltages at the battery, with:
The car off?

The car idling (warm idle, if you can)?

The car at 2K RPM?

One can have the entire system checked for free at many parts stores. Or remove the alt and take it in for a bench test.

Battery cables need to be in good condition too. And James is right about the fusible link. More info is simply needed IMHO.
Good luck.
 
car off 12.6(multimeter)

car idling, but not fully warm 10-11v or so (OEM voltmeter on dash) and idle fluctuates and car sputters and regains, sputters again, regains...etc. almost sounds like a mild cam, lol

holding at 1.5-2k rpm the voltage rises to 12v+(according to the OEM voltmeter on the dash) then drops back down upon release and the fluctuating idle begins

technically the alternator should be fine since its new(although I have heard of some "new" ones being duds) and I know the battery isn't at fault because I fully charged it with my charger and even tried another battery from a buddys car with the same results :shrug:

another bit of info, when I drove the car around the block last night(old alternator w/ UDP alt pulley) the car was sluggish and would die when ever I came to a stop. it started back up but the lights were very dim and it was underpowered...thus why I bought the new alternator today. (FYI: before this issue last night it ran fine)

I figure I'll check the fusible link and the associated wires tommorow and report back

any other ideas, let me know guys, thanks

HISSIN50 said:
So what are voltages at the battery, with:
The car off?

The car idling (warm idle, if you can)?

The car at 2K RPM?

One can have the entire system checked for free at many parts stores. Or remove the alt and take it in for a bench test.

Battery cables need to be in good condition too. And James is right about the fusible link. More info is simply needed IMHO.
Good luck.
 
The fusible link is probably ok - it sounds like you have some sort of charging occuring, otherwise, the system would constantly be in a state of discharge. It takes 10 seconds to grope it and see how the link feels so that still sounds like a good plan. :)

I have gotten bad reman'd alts right out of the box, but new should have a better chance of being ok.

I really would get a real voltmeter to check this stuff with. The stock meter is not accurate to start with. If you have any voltage drop in your almost 20 year old wiring, that will skew readings.

Harbor Freight puts meters on sale for 4 bucks all the time. That is a great thing to have, if you dont have one.

If the alt and car work decently if you hold the throttle at say 1000-1100 RPM, then overdriving the alt might help out.

Otherwise, a once over on all the wiring sounds good. Do make sure all the connections are tight - a loose connection causes some funkyness (been there and done that).

Just my random thoughts.
Good luck.
 
this situation is eerily similar...

http://www.mustangforums.com/m_516158/mpage_1/key_alternator/tm.htm#516158

ORIGINAL: adam519

Hey folks hope someone can help here... I have an 88 GT converted to mass air and out of the blue i developed a charging issue...

I have tried 4 alternators to no avail, with car at idle and thru RPM range the battery reads 11.85v and then with the car turned off it reads 12.10 or slightly higher or lower. There is a lil square device on solenoid, is that an external volt regulator?

Anyhelp is appreciated

ORIGINAL: adam519

well the fusible link for the alternator is cooked... wire broken right in half... originally looked like it was a nick in the wire coating NO voltage at all at it thanx mustang8719, will keep you posted on my head ache

ORIGINAL: adam519

HEY mustang8719, there is also a fusible link under battery tray... the acid corroded it... repaired wire and guess what buddie... i am charging from alternator again!

THANK YOU SO MUCH FOR YOUR HELP..... I CANCELLED THE APPT FOR THURSDAY

WILL KEEP YOU POSTED ON HOW SHE HOLDS OUT
 
TheUser said:
you *might* be on to something. There's a black/orange 10ga wire that runs from the alt. to a 14ga green fuisible link...it merges w/ another wire at the fusible link, I believe. Check the black/orange wire and inspect the fusible link. You should be able to buy fusible links and normal wire at autozone in the electrical section.

If the wires pass a visual inspection, I'd unhook/unplug them from anything they're hooked up to (not necessarily remove from the car, just unhook from components) and use a digital multimeter to ohm out the wires and see if you have a bad spot.

With a new alt and a good battery, it almost has to be the wiring; new products can be faulty, but since the old and new one had the same issue...

Good Luck :nice:

+1

Everyones telling you to swap altenators when you can probably check wiring.....Check wiring, and upgrade if needed. those wires get mighty crispy after 10+ years.
 
well, i checked the fusible link today and just retaped the connections and than cleaned the connectors on the alernator and the car held 11-12v at ilde and the fluctuating idle calmed down significantly(IAC clean is next).
one thing I noticed was that when the gas was pushed voltage would go up to 13-14 volts...so I'm banking on the crank and WP underdrive pulleys being the remaining culprits. I just bought an OEM crank and OEM wp pulley, so I'm praying with those I'll have it back up at 13.5-14v or so. Thanks for all the help, I'm hoping this issue is almost done with :nice: