I'm having a very big problem with my 66 F-100
I have replaced the alternator with a new one, a voltage regulator with a new one, and it still won't charge.
I've even cut the wrapping off of the "shrink tape" stuff that is over the wires that go from the alternator to the voltage regulator and traced them and made sure it was hooked up right.
The red power wire I have from the alternator I have hooked directly to the battery.
The battery show about the same reading running or not (between 12.6 and 12.8 volts)
So what could my problem be?
Any help would be appreciated

 

Try this first:
1. Connect a voltmeter red to bat connection on alternator black on engine while running. If you have any voltage above your 12.8 volts, the alternator is charging.
If 12.8 or less, replace alternator
2. If yes in #1, check red wire for a tab of rubber (fuse link) probe the wire on both sides of this fuse and check for continuity with an ohm meter or continuity tester. If no continuity, replace fuse with suitable replacement fuse link. If you have continuity, see #3.
3. post back with the results as you may have other problems.

 

Problems there.... 1 No fuse link in wire
2) I cant check alternator with it running, its to close to the block.
3) Its a new alternator and I've tested it off on a tester at the store
So I dont know what to do

 

While I will agree that the alternator tested fine at the store, it may have been shorted/ruined when installed and ran. If you removed it and had it tested, it should still be good. That's why I wanted to test it in the truck. Try using a screwdriver as an extension of the voltmeter lead. Can you reach the BAT lug that way?
Did you have the alternator and the regulator tested together at the store?

 

Yup, I had the alternator tested at the store. I bought it, installed it, no charge, took it back and had it tested.
I bought the alternator and a volt regulator at same time just to be safe. And I dont think I can get to the battery post of it with it on the truck, its very close.
I dunno what to do now tho.

 

It sounds like you have a wiring problem then. If both components work on the bench. Looks like your going to have to unbolt the alternator and attach a "test" lead so you can perform some tests on your harness. It's the only way to get to the bottom of the problem.
Do you have a charge light ( BAT, ALT) in the cab? Does it light up when you turn on the key but not starting the truck? If not, your bulb is out. I know it's a dumb question but if it is working but not lit up while the truck is running, we can help isolate the problem.

 

That's a good point there.
I have an ALT light but it dont light up while running
I never bothered to check it w/ turning the key on but not starting it. lol
I've stripped the shrink wrap off of the wiring harness that goes to the regulator and its all good.
Dunno what else it could be

 

Since you have everything peeled open, Check ALL of the connections. Battery terminals, alternator connections etc and make sure they are all clean and tight. Anytime there is very high resistance in connections, the current has no place to go or will only trickle out giving false readings. I wish I was there to help because typing is a pain in the butt.
Let us know what you find if anything and I will continue to try and help.

 

I already checked them
I appreciate the help
The wires from the harness to the alternator are all good and looked brand new underneat the wrapping.
The connections to the alternator are all brand new crimped on ring connectors (cant think of the name for them)
and the red wire from the alternator to the battery is brand new also.
Battery terminals have been replaced also..
I wish you were here also.
lol

 

Andy , go buy yourself a two or 3 gauge setup (i.e.-volts , water temp. , oil pressure) and mount it temporarily in the engine compartment with just the voltmeter hooked up!!!that way you can monitor the charge voltage from the alternator until you find your problem , then you can go ahead and mount all 3 gauges onder your dash AFTER you have fixed your problem. Just a thought!!.......fd

 

Good idea.
I might try that... It'll be next week tho... cuz im going JUNKYARDING this weekend, and gotta save cash for that :P

 

Are you sure that your alternator is not charging, or when you get in your truck in the morning your battery is dead. If you start the truck and take off the battery cable and the truck stays running, then your alternator is working. If that's the case you have a draw in power somewhere. The first place I would check is your starter, it has power to it all the time. If something starts to wear, it will draw your battery till it's dead. I've had this happen to me twice and pulled my hair out trying to figure out why my battery kept going dead.

 

The battery I'm keeping on a trickle charger in the garage. The 66 sits behind the house (waiting on friend to pay up for his 66 I sold him before I get tags)
The alternator is good, the volt reg is good, wires are good.
Ive check wires from battery to solenoid, battery to alt, alt to volt regulator... all good.
It just shows like 12.6 volts when its running and it should show more than that... like 14 or so right?
Because the voltage doesn't go up when its running. I can check it, have 12.6, start it, check again... it shows the same..
I still haven't figured this one out, but I gave up on it a few days ago... decided to do something else for a few days.
I'll check on it again tomorrow.
Thanks again for the help

 

Hey Andy,

mwc4275 is right. Disconnect your battery while the truck is running. Be careful though...it could be an electrifying experiece if done wrong If the motor dies...your alternator is bad. If it doesn't...it isn't.

I'll have to go out and look at my truck tomorrow, but there is one other possiblity. I'll get back to you tomorrow night (sun).

 

Hey,
The alternator is good... I've checked it that way, and on a tester at the local O'reillys. If you come up with the other way to test something, please let me know... this wiring problem is getting on my nerves something bad.