Have 86 F250 Ext cab. 4x4w/460 and is carb. Prior owner put a 2bbl on and truck was running ok till today. Trying to get carb to stop surging after truck warm and adjusted the elec. choke a little leaner. Truck idled ok and took it for a ride...no other issues than kinda hard to crank over and sometimes starter would stall a bit and then crank truck over..cold or hot.

SO riding down road for about 10 min..no surging, etc. Stopped to look at 2 houses for sale by me and truck idled no issues. Got back on road and doing about 50mph, 2500 rpm or so and truck dies..like not getting any gas and then put in neutral coasting down road and truck fires up...then sputters and dies again...

Looked down and saw the charging gauge was pegged at "C" and tach was going crazy.. pulled over and tried to restart, which truck wouldn't do..no cranking, anything. Tach went to 6K and stuck there for a bit.. jiggled battery connections and truck fired up and tach went to correct idle...then truck won't idle for more than 30 seconds and won't move out of its way... had her towed home.

Popped hood and saw the positive cable from battery to solenoid cooked and melted by terminal and terminal connection on wire started to cook/melt.. WTF...have no clue but saw possibly alternator, starter, or fuel pump??? Think I have an electrical demon but wanted some other input if the 3 things I mentioned could be problem too?? Gonna pull starter and alternator off and have checked at local parts store..other than that??? HELP... any thoughts? Not proficient with carbs since grew up at the time when they were phased out (80's/90's)..if it was elec. issue, no problem..and no idiot lights either??

 

Ok, just fired up truck in driveway and when cranking, starter didn't want to turn, then would crank and truck would fire and then conk out.. lights in the cab went very dim and then out when cranking. Seems like starter is drawing a ton of amps... oh yeah..when it was running, I idled at about 1800rpm and the charging gauge was pegged at "C"..then I left off the gas and the truck went to idle about a 4 seconds and conked out..seems like not getting any gas, but the overcharging thing has me perplexed??

 

You have been bitten by the infamous 2G alternator "Fire plug"

The charging harness from the alternator shorted out and when the truck didn't think it was getting power the alternator went full field, melting the already undersized wiring.

There is a Technical Service Bulletin on this issue.
Many of us that have encountered the problem have upgraded to the later 3G (third Generation) alternator, that solves it.

http://oldfuelinjection.com/index.php?p=75

 

The harness is shorted out.
Remove the fusible link with the two orange/black wires from the starter solenoid and the battery drain should go away.

Charge the battery with a charger.
Replace the alternator's charging harness, with the plug.
Likely the alternator has suffered fatal damage..

If that is the case, I would recommend upgrading to a 3G alternator and wiring harness.

 

If you have no lights in the cab, one of the fusible links on the starter solenoid has likely burnt out because of the excessive current.
These are thick wires with a little rubber 'ear' at the lug end.
Replace with a generic one of the same color (gauge) i.e. green is 14 Ga. and intended to protect a 12 Ga. circuit...



I doubt the starter was affected, just that you now have no power reaching the ignition switch to energize the starter relay.

 

Damn, that's the only parts I didn't give you, an alternator and harness.

 

Thanks for the info. Pulled the alternator off yest. and had tested today at local parts store. Alternator tested good. Was looking and wondered if the voltage regulator was toast?

But Ard, that looks like what happened..as soon as I fired up the truck after this happened..man, the charging gauge pegged full charge..

as far as the lights, they only dimmed almost to the point of not being on when I was cranking the truck..when running, or not cranking, lights fine, well for 1986!! Pulled starter as it looked weak and saw some of the teeth were worn..its like the started didn't have enough oomph and was thinking about putting on a high torque model?

Just saw the battery cable from batt. to solenoid was toast..looked to be previously replaced, but got so hot other day, it melted some of the sheath near the batt. terminal... was thinking about replacing the solenoid also?

SO, hopefully, if I upgradge the wiring harness, get a new alternator, and replace the solenoid and pos. battery wire from terminal to solenoid, should be good to go? Maybe the ignition control module too?? Was on closeout from retailer for $10 bucks..figured good to upgrade that too?
Thanks for the help!!

 

The ignition module is likely fine.
If you have an original Motorcraft DSII module I would say keep it.
The $10 module would be cheap insurance to keep in the truck.

I don't believe your local parts store, but I have been wrong before.

If you are going back with a 2G (external fan)alternator be sure to replace the output plug to solenoid harness. This is what fails-at the plug-
If the regulator is toast, and you are replacing the associated wiring anyhow, I would upgrade to the 3G style alternator to avoid any future problems.

You can see that both Bill & I have gone to the later PMGR style starter.
I did this because I was sick of the fender mounted solenoid failing.
But it is more compact and does spin faster.

 

To say the person at the parts store knew what they were doing with the test would be a HUGE improvement over what I saw..they didn't even ground it right the first time..

I think I will upgrade to the 3g alternator..I do have the external regulator on the fender..will this be a problem or is it just a simple swap with the new alternator? Any links to the correct wiring I can use or is it a plug and play?

 

Oh, I did not realize you would have an external regulator (1st Generation) alternator as late as '86.
They were mostly found in diesels that late.
If you have an external regulator, you may be okay...

There are many threads on here about swapping to a 3G alternator.
No, it isn't quite as simple as "plug 'n play"

If you have the fender mounted regulator, this should be a simplified wiring diagram as it is now.



And this would be how the 3G is wired into a truck like yours.



You should probably use the 8.25" ear spacing version from a 3.8l V-6 in a Taurus/Sable.
You will need to put a thin washer behind your V-belt pulley when you swap it over for the serpentine pulley used on the donor car.
Or the pulley will rub the case of the 130A alternator.

If you get yours from a pick ' pull, be sure to get the heavy charge cable and fuse from that car too.
Or you can order anything you need from RJM Injection Tech. (then it really IS "plug 'n play").
RJM Injection Tech — Alternator Accessories

 

The Taurus/Sable alternator Jim is referring to is a drop in on a V belt 460. RJM technologies sells a wiring harness as Jim mentioned, or a complete kit, alternator included. If you go to the Virginia Beach Pick and Pull there are usually plenty of the older 3.8L Taurus/Sable models in there 1995 was the last year for the 3.8L in these cars. Lincoln Continentals through the 1994 model have the same engine.

The Taurus charge cable runs clear across the front of the car and back along the left fender to the underhood fuse box where it attaches through an 18ga fusible link (remember, I own one). You would be better off to buy the kit and just grab the alternator at Pick and Pull.

 

It seems you two know each other...

Yes, there is plenty of cable if you pull it all from a donor car.

One thing that needs to be done, is to tap the clamping ear of the alternator to 3/8-16 for the sliding bolt.

If you don't go to the junkyard you can buy the shim washer, charging cable and regulator harness from RJM.
All you need to connect is the Lt Grn/Red wire that is now going to your regulator, the 'new' charging cable/fuse to the battery + side of the fender mounted solenoid, and the yellow wire from fused power to the truck harness as shown above.

Dispose of all the extraneous stuff.

 

Yes, I gave Ryan all the remaining carbureted and V-belt stuff from mine. He works in Norfolk.

 

Hey All,

Sorry, have the internal regulator..was late night last night and wrote wrong info. So, I am headed to local u pick it to snag an alternator off of a taurus w/the 3.8. I ordered the harness adapter kit from a place in PA, PA Performance and now, the only thing I guess I need to do is wait for that, then get the megafuse 175, and hook it up.

Was looking at the elec. choke issue and guess the harness I had ordered doesn't have the wire for the choke, but I saw in another thread how to hook it up to the alternator, think it was the "s" cable, but don't quote me, I'll look before wiring it up...

Saw a picture of a burnt up alternator harness...wow, no wonder you guys called it "fire plug"... Thanks for all of the help so far..it has been great!

 

Ryan, you tap the white/black wire for the choke, it is the "S" lead. The 2G alternator was also referred to as the "Flaming Ford".