alright yall,

1986 F150 5.8L (351w). The fusable link at the solenoid on the fender burnt. It is the one that ties into the harness that the alternator is tied to. I replaced and went to go to work (3 miles) and the battery drained half way there. The link did get hot also. I took the battery to work and charged it. I put the battery back in and tried to get it back to the house. The link smoked right off the bat.

Can the voltage regulator be pumping to much juice? I am assuming the alternator bad cause of the battery drain.

I could use some ideas guys. Any help at all would be really appreciated.

Thanks in advance.

 

My best guess would be that you have a shorted diode in the alternator.

 

well I went to the zone this morning and picked up another fusable link. Good thing they are only $3.

I disconnected the alternator, and installed the link. The link got warm instantly. I drove the 1 mile home, and got her parked. I popped the hood and stood there and watched as the link started to smoke and then pop. The weird thing is that the alternator started smoking too. (remember it is unplugged from the harness)

The alternator plug was twisted, so i untwist it and both wires were bare and touching. I am thinking this could be a short right?

So i have to buy a new alternator (figured as much), and replace the plug. Can i get that plug new? Is it time for a field trip to the graveyard?

How can i test for shorts?

Thanks in advance

 

Ok, the zone has a 61 amp alternator for $45. It is old school and does not require the plug. I just have to snip the old plug and clamp on the eyes.

Is 61 amp to small? I am short on funds and this one is $35 less than the next wich is a 70 amp. I dont have power anything but i do have AC.

 

Most 70 amp alts are larger case units, and swapping between the 2 case sizes *can* be difficult. If the 61 amp is the same case size as your old unit, go for it.

 

Thanks Rogue_Wulff,

I will check that out. I am going to pull the old one before i buy the new one, so i can match it up at the store.

I appreciate the imput!!!

 

You need to figure out what type alternator you have. If you have a internally regulated alternator, then you can't put the "old school" alternator in it's place without a bunch of re-wiring and adding a external regulator.

 

Franklin is right you need an internally regulated alternator.

The 1st generation (1G) alternator you're talking about is anemic and needs a whole separate regulator mounted somewhere plus hacking up your existing harness.

Replacement 2nd generation (2G) alternator plugs with pigtails are commonly available. Many remanufactured alternators come with one and their warranty states you must replace it.

If you want an alternator with a lug instead of plug go with the later 3rd generation alternator. These were designed to solve the woes of the 2nd generation alternators (poor charging at idle, a plug that starts engine fires)

If you're broke measure the distance between the pivot bolt and the adjuster bolt of your current alternator then go to a junk yard and find an early 90's Taurus with a V6.

You need not only the alternator but the heavier charging cable and a chunk of the harness coming from the plug.

Then you'll need to tap the adjuster hole to fit the 3/8-16 bolt already in your truck.
Remove the serpentine belt pulley and swap it for your V belt pulley placing a thin washer behind it so it doesn't rub the housing.
Find the green/red wire in your alternator harness and splice it into the 3G's plug.
For your safety you should add a heavy duty inline fuse to the charging cable.

Many of us have done this conversion. Just search for "3G alternator swap" here, or on the Full Size Bronco forum.

This is an informative link: Ford Fuel Injection 3G Install Tech

 

As pointed out, if you have the internally regulated alt, then that's what you'll need to buy. 86 could have either style. Typically, a carbed engine uses the external regulator, and EFI uses the internal regulator, but this is not always the case.

 

Thanks for all the info guys. This is exactly why we come here.

I am off on friday and its my B-day. So i am getting myself an alternator.

Any ideas on tracing down shorts?

thanks again all.

 

It just so happens I just aquired a 86 ranger. I found out it had the dreaded 1st generation internal regulator alternators from Ford. I believe it's called a "2G". I looked up a replacement and they are not cheap, and I saw all the "replace the plug" warnings.

So what I did was put a GM alternator on it. I had to re-work the bracket a little bit and drill out the hole on the GM alternator, and got it to fit fine. Hooked the Ford green/red wire to terminal #1, put a small jumper from terminal #2 to the output post, and ran the two black/orange Ford output wires to the output post. Works great.

 

Buy a manual with the schematics color coded and a decent VOM (multimeter).
Disconnect the fuseable link that's burning and start tracing the part of the harness connected to it.
I have no idea where to start unless it's in front of me. (what section of harness is affected)
You might set the meter to ohms, connect between ground and the link and then start pulling and replacing fuses one at a time until the scale reads close to infinite.

Edit: Happy Birthday!

 

Dave, why did you go with a GM alternator when a later model Ford one takes the same or less work to install and has a better output profile?

 

I just re-read this and realized you say it is the alternator harness that's burning up.

You asked if we had any ideas for tracing this short.
Most likely the infamous plug is melted and shorted internally.
The pigtail is available separately for under $10.

Borg-Warner PT-780
Standard Motor Products S-542
Power Plug 4628011
KEM Parts 350-220
Pico 5711
Dorman/Motormite #85123 / 08622
etc.....

But if you need a new alternator because of it I would take the opportunity to install a newer one without all the problems.

 

ArdWrknTrk thanks for all the great info.

My alternator has 2 plugs. Would you happen to know what the other plug is?