Alternator Wiring in 1975 V8 Ford 302 Bronco?

[MerganserMaster]

I am working on fixing the wiring in a Bronco (with a V8 302 engine) that squirrels have lived in for a while after it was "stored" outside. The wires leaving the alternator are severed and I am unsure as to where they attach. Based on another severed wire that I see in the engine bay it appears that the large black wire (seen in the first picture) and the smaller red wire are supposed to go into the voltage regulator located in the rear left (passenger) side of the engine bay. However, this leaves the third wire (I believe its a white-ish color) without an obvious connection. Is one of these wires a ground or supposed to hook up to the battery side of the solenoid? I could not find much information online or in my repair manual. Any help is appreciated, thanks!

https://flic.kr/p/2oG86it
https://flic.kr/p/2oGbbi1

 

[DirtDonk]

The large black with yellow stripe wire continues up to the body harness through at least one connector and through the firewall.
It runs through the under dash area over to the ammeter and then back out to the firewall and is black only, or black with a red stripe as it runs out to the battery side of the starter relay.
This is the main charging “loop“ that powers the vehicle and charges the battery.

The Orange field wire runs directly to the voltage regulator’s “F“ terminal.

The white with black stripe stator wire runs straight from the alternator to the carburetor choke connector.

I don’t remember where each of these had a connector, but they are not direct single runs that I’m aware of.
There are connections somewhere under the hood. Just not sure where on a 75.
But those are their functions.

 

[DirtDonk]

Oh, and see where the “strain relief“ has a metal tab that attaches the whole wire harness to the back of the alternator? That is the ground connection.
And from the molded rubber, the small black ground wire runs over to one of the voltage regulator bolts on the firewall.

 

[Oldtimer]

Courtesy:

SeaBiscuit68

 

[DirtDonk]

By the way, MM, welcome to Classicbroncos!

And oh, by the way number two, when you take that alternator off, as you are very likely to do just to make it easier to work on, please take some pictures of the back orientation and colors of the round insulators around the post/terminals.
It’s just for the archives since most of the alternator manufacturers have changed the colors to something completely unrepresentative of the original colors of the wires.
So nowadays everything comes in black or white or something, instead of the original red for the BAT terminal, orange for the FLD terminal, and black or white for the STA terminal.

So it would just be nice to see what an old, possibly original, alternator looks like.
Hopefully you get the chance to do that.

Thanks!

 

[DirtDonk]

And it might be good that you noticed the crappy condition. Might not even have been the squirrels entirely, as the age of things could have taken their toll as well.
The relatively dirty and corroded looking condition of the connections at the ends of the wires means it really would be a good idea to at the very least, clean them up to see if they could still be used, or replace them entirely along with some new wires.

 

[MerganserMaster]

Thanks! If I end up removing it I will take some pictures and upload it to the forum. It had some modification done to it as the manual transmission shifter was "moved" from being on the steering wheel to being on the floor. I am currently just trying to get it running (even if just on starter fluid) as it was "stored" outside for 20 ish years but I have got it to the point where the starter and engine turn over when the starter solenoid is bypassed. It was last running in the year 2000 so I am hoping it needs no new major parts. In anyones curious, the bronco in question is the bronco in my profile picture.

 

[DirtDonk]

Nice. Is that a brown, or more of a copper color?

Thanks ahead of time for any pictures you’ve able to share.

Cranking when bypassing the starter relay is a good sign. At least it means that the battery, cables and starter are all good.
If you haven’t already, try “jumping” the relay too. That’s where you jump just from the battery to the small “S” terminal where the Red w/blue stripe wire goes.
If it cranks then you also know that the relay/solenoid is good as well.
Or is that what you meant by bypass?

 

[Steve83]

I am working on fixing the wiring in a Bronco (with a V8 302 engine)...

You should put ALL your truck's details & history (as much as you know) into your signature(<-click that) so it shows with each post, as this page explains:

(click this text)


Put your location (nearest city) in your profile &/or signature. The more pics you post (NOT in your sig) of the truck, engine, wiring, labels, & undercarriage, the more likely we can help you. Not all its details are relevant to these issues, but you don't necessarily know which ones are relevant, so just put everything in now.

 

[MerganserMaster]

Long Overdue Update: I have successfully connected all of the right wires to each other (via trial and error) and the Bronco now turns over when the key is turned (and the radio works to ~ very fancy!). However I am having a difficult time getting it to actually start, it backfires occasionally when starting but it did make a "puht" noise once. I have replaced the starter and am now going to replace the battery as those were my first two concerns with the not-starting-issue. I have jerry-rigged a gas can with a tube in it attached to the fuel pump to act as a "tank", so I do not think bad gas is the issue. If the new battery does not work, then I will have to think of something else. Big thanks for everyone's help.

 

[DirtDonk]

Stop replacing parts!
Reason I shouted that out so much is, that from here at least, your description sounds nothing like a battery or a starter issue.
Is the starter spinning and turning the engine over (cranking) when you turn the key to the START position?
If so, the starter is working.
Does it sound like the starter is cranking/spinning/turning the engine over at a normal speed?
If so, there is nothing wrong with your battery.

The symptoms you describe sound like your ignition timing is off. I have not re-read your original post yet to see what you are running, but presumably it's a distributor type ignition. And you had the distributor out at some point?
And speaking of points... Do you have a points type distributor, or electronic? If points, just sitting unused for awhile would be reason enough to clean, re-adjust and re-time the ignition.
Don't just throw parts at something when they might not be bad. You have to either test them, or dig deeper, because even if your starter and/or battery are going bad, there are many other things that keep an engine from starting.

paul

 

[MerganserMaster]

Thanks for the concern, I can easily see how someone could get carried away with replacing parts. I knew the battery and starter were bad because I had them tested. The distributor is electronic and I am getting a "spark". Is there a way to test an electronic distributor to ensure it is working properly?

 

[DirtDonk]

Yes. But if you are getting a spark, it is working.
You need to check your timing anyway, just to be sure.
Another thing related to timing, would be if you had removed your spark plug wires. It's very easy to put them back on out of order, so if you did have them off, triple/quadruple check your plug wire order against the firing order.
This is an engine you have not touched internally and are just trying to get it running. Correct? Did you mess with the plug wires at all?

You can check the distributor's internals with an ohm-meter. Separate the two halves of the wiring connector and with your ohm-meter, check the two "colored" wires. I think they are Orange and Purple with black stripes? Whatever their colors, you don't need to include the Black w/white stripe one, as that's a ground.
However, it would not hurt to make sure that one has a good ground connection. It's screwed to the body of the distributor inside under the cap, and then is grounded through the fender i believe, over at the module.
Is your ignition module (modulator in Ford-speak) bolted to the driver's fender/wheel well?

How's about some more pics? Some general shots of the areas around the top of the engine, the battery and starter relay/solenoid on the fender, driver's side fender near the wiring, and any other areas you think might be pertinent.
What about vacuum hoses? A '75 would have had plenty from the factory, but many get removed by owners wishing to clean things up or get rid of "all that smog crap" as they like to say. Maybe you have some vacuum leaks. That would also sound like bad ignition timing and have similar symptoms to what you're describing.

So my vote is for more pics!

Paul

 

[DirtDonk]

I forgot to add a detail. A minor one…
When you’re checking between the two wires, you’re looking for a reading of between 400, and 800 ohms.
Anything outside of that, or near the extremes, warrants a replacement of the inner stator.
Easily purchased through just about any auto parts store.
Also relatively easy to replace, but it’s just another reason to have a timing light handy to check ignition timing after replacement.

 

[MerganserMaster]

I have not checked the distributor resistance yet, but here are some photos of the engine (please excuse the crimped together wiring as it is temporary). Notice there is a "spout" with no tubes/hoses attached to it on the top-left side of the engine, is this supposed to be connected somewhere?

https://flic.kr/p/2p3r36T https://flic.kr/p/2p3r5ng

 

[DirtDonk]

Notice there is a "spout" with no tubes/hoses attached to it on the top-left side of the engine, is this supposed to be connected somewhere?

To the air cleaner housing.
It is your "fresh air return" for lack of a better term. It's the backside of your PCV (positive crankcase ventilation) system and is very important.
Every time you run the engine, outside air is being sucked into the engine through that fitting. So it needs to be connected to the clean air side of the air filter.

Notice in the driver's side valve cover (literally the opposite corner to the fitting you're asking about) there is your oil filler cap with the PCV valve sticking out the center.
The valve is connected directly to engine vacuum, usually at the base of the carburetor, and sucks dirty air from inside the crankcase, back into the intake where it's burned along with the new air/fuel mixture.
Because it's sucking out the bad, you need the other fitting to be sucking clean air back into the crankcase.

You have a rarity there, in that the carburetor still has the bowl vent for the charcoal canister, and the data tag under one of the top screws.
It's very possible that you have the original carburetor. If not, then at least someone went to the trouble of getting the correct replacement, and leaving the data tag on the new carb.
Either way, the point I'm eventually going to get 'round to, is to NEVER throw away the tag, or let it go with your old carburetor as a core for a new one.
In fact, even if you do get a new or rebuilt carburetor, don't get rid of the old one until you know for certain that the new one is the same thing.
Once it's been turned over as a core, your old one is virtually gone.

Speaking of the air cleaner and the charcoal canister (evaporative emissions system, or EVAP), that 3/4" diameter fiber-like hose sticking up behind the wheel house is from the charcoal canister mounted to the frame rail. There should be two of them.
One goes to the air cleaner, and one just stays there letting outside air into the canister.
The bowl vent with the hose on top of your carburetor should go down to the canister as well.

Paul

 

[MerganserMaster]

So is there anything you see from these photos that needs to be immediately fixed (i.e. any non-attached hoses)? I believe that the hose to the charcoal canister is still attached as I remember seeing a canister in an area similar to the one you were describing. Also would the fresh air return still need a hose to operate (in the short term) or will it still operate "as is"? I'd have to look at the air filter for a spot for a hose to connect but I believe it may be an aftermarket air filter as it seems a bit out of place. Here is an older photo of the engine with the air filter on it (I still have the filter I just take it off to create more room when working on it):

https://flic.kr/p/2p3xNpw

 

[DirtDonk]

That is a factory bronco air filter. Hang onto it!
There will be at least two fittings on the passenger side. One is in the round housing and is for one of the hoses from the charcoal canister. The other is underneath in the flat section between the carburetor and filter, and that is where the elbow fitting on the valve cover attaches.
Hopefully that one still has the custom molded curved hose.

 

[DirtDonk]

Oh, and no, you don’t need it connected while you’re sitting there, trying to tune things up or clean things up.
But you absolutely need to have it connected to a filter of some sort if you’re going to go out driving very much.

I think it would be much more fun to work on everything if you cleaned up the engine department somewhat.
Just make sure to cover things like the carburetor and that port before you do much cleaning.
One reason to clean it now is that while you are running it, the fan might blow debris around the engine compartment and get sucked into the engine.

 

[gr8scott]

You should, at the very least, get some new plugs and wires.

https://www.napaonline.com/en/p/BEL700160

https://www.napaonline.com/en/search?text=spark%20plugs&referer=v2