fuse fried, need help

[roostracing]

Does anyone know the size or what part # is needed to replace the fusible link that goes from the voltage regulator (A) to the starter solenoid? It is the wire that has a thinner yellow wire and a black wire, then goes into a fusible link, then connects to the starter solenoid. I noticed mine was frayed and only half of the wires were still connected. I cut the stock fusible link out and replaced it with a regular fuse. It was just a 15 amp and i blew it. Bronco completely dies on the hwy. I installed a 30 amp fuse and it cranks over now but will not start. The sudden jolt must of have fried something since it no longer starts. I cant hear my electric fuel pump so i think it toasted it. The electric fuel pump was not wired to a relay and straight to a power source with the key on. Luckily i bought and received my new carter pump a few days ago along with a relay. Hopefully that is the problem and nothing else. I was having charging issues and saw this wire so i tried to correct it.

I want to replace that regular fuse i installed back to a proper fusible link. All help appreciated!

 

[DirtDonk]

Can you post a pic of your starter relay/solenoid area so we can take a peek at the wiring?
Stock wires, or aftermarket? Can't remember if we talked about that before or not.

On your '74, the stock wiring might have included a Yellow wire with fusible link "tab" (orange-ish brown maybe?) at the starter relay that's for powering the horn relay on the fender skirt. Do you have that horn relay? Yours would have been the first year Ford installed those on EB's, but not all '74's had them.

How many wires are there on the battery side of the starter relay? Usually only the three from the factory. Large Black (maybe with a red stripe), Yellow, and the battery cable.

Paul

 

[roostracing]

2 wires come out of voltage regulator under the (A). One is a ground resistor that is grounded at regulator screw. The other travels to and connects to a fusible link (now new fuse),then connects to thick black wire going to positive side of starter solenoid.

I have 2 wires connecting to the starter solenoid. The one I mentioned and a yellow wire which goes back to fire wall in a different wire loom.

 

[DirtDonk]

So the fuse is just in the yellow wire though, not the black, correct?

I didn't know the Yellow wire to the regulator had it's own fusible link. But either way it should never blow a 15, much less a 30 amp fuse, so something is shorted either in that line or the regulator itself.
Nothing that should have blown a fuel pump though, I wouldn't think. Maybe it hurt the contacts in the ignition switch? As opposed to the main power to the pump, maybe it's the switch instead?

The little thingy at the other Yellow wire is a radio noise suppressor, and it can be disconnected for testing. Maybe it got buggered and is now grounding through it's case. I've seen that happen to both the ones on the regulator and the ones on the ignition coil. Only the one on the coil would effect the engine starting though. The one on the regulator would only mess with the charging system or blow fuses.
Disconnect it at it's plug (if it still has a plug) and see if that helps.

Is your charging system working properly?
Is your horn working?
Is the engine cranking "normally" at least, or is it slow?
What about the pump again? How is it wired exactly? Probably too much for the old stock ignition switch to handle without a relay, so wondering.

Paul

 

[roostracing]

No the thick black wire is the one going strait to the (A) of the voltage regulator. This same wire (about 6 inches away ffrom the starter solenoid goes into a fusible link which then ties into a yellow thinner wire. I was told to put a regular fuse instead. The only reason I cut and spliced this wire is because the wire seemed to be coming apart at the fusible link part. I had the turn signals and brake lights fixed and noticed that when I got it back,it wasn't charging anymore. I decided to put a new battery, alternator (60 amp), starter solenoid ,and voltage regulator. The stuff currently on there was pretty old so I figure I couldn't go wrong. Well it still didn't charge and the guys at O'Reilly did a test on the bronco with their auto meter hand held device. It said voltage regulator failed.

My horn is aftermarket.

Engine cranks normal. It just doesn't start. I do not hear my fuel pump either. It is connected with no relay and straight to an ignition source for power.

 

[roostracing]

Here are some pictures.

 

[roostracing]

Some more

 

[DirtDonk]

From the factory, the thick black wire does not go to the regulator.
The yellow wire splices to it and feeds the regulator full battery voltage all the time.
Now, an owner installed black wire is a different story of course, but the factory Black wire to the starter relay is the one that keeps the battery charged and powers literally everything on the truck when the engine is not running.
If you follow your black wire from the starter relay, can you see where it's still connected to the rest of the harness without going to the regulator? If so, great. If not, and it's spliced into the regulator, you'll have to change it back to factory routing to get anything to work properly.

The usual colors to the regulator are as follows:

F - Orange
S - Green w/red
A - Yellow
I - Not used on vehicles with an ammeter.
Mounting bolt - small Black w/red wire (ground) to the alternator. The other bolt, or even the same one, can be used to attach the radio noise suppressor.

If yours is like that, it should work once you've got the regulator replaced.
Where is the pump connected?

Thanks

Paul

 

[DirtDonk]

Ok, thanks for the pics.
I see the little horn relay there near the starter relay too. So one Yellow wire is going there at some point.

Can't tell exactly what's going on under the wire loom, but if that fuse is indeed in the Black wire, that would explain the blown 30 amp fuse. Because your alternator is capable of at least 60 amps, you need a suitable fuse or fusible link in that line.
Ford always used a fusible link, as do companies like Centech, but other aftermarket harnesses makers like Painless use a Maxi-Fuse rated at 60 amps to protect the cabin circuit, and Mega-Fuses rated above the alternator's capacity for the charging wire.
We use 175 amp Mega-Fuses in our 3G harness because of it's 130+ amps capacity.

Paul

 

[DirtDonk]

Does everything die when that fuse blows?
You could test that theory of overloaded fuses in the charging wire by replacing the fuse with another one in the 10 amp or even a 15 amp range, and start turning things on in the cabin.

With the engine off, just turning on an old heater and the headlights would quickly blow a low amp fuse.

Paul

 

[roostracing]

First off thanks for helping me out!

The black wire from the solenoid eventually connects to the yellow wire which goes directly to the (A) of the regulator. I will have to check where the black wire goes after it meets up with the yellow.

The fuel pump red wire splices into another hot wire under the dash.

 

[DirtDonk]

The fuel pump might have trashed the stock ignition switch, which would lead to some, or all of these issues.

Paul

 

[roostracing]

Yup,that black wire goes to what I had (15 amp) fuse which blew. I put a 30 in and it turns over but will not start. When the fuse blew,I had absolutely no power what so ever in the bronco. No crank,no lights, no nothing.

 

[roostracing]

Are all fusible links the same? Or ate there different ratings?I want to put one back in and take out the one I installed.

 

[roostracing]

I am also going to install the carter pump tomorrow. Hopefully everything is back to normal. I will be using a relay. Obviously the relay will go to the battery but the other power source goes to any ignition source with key on only?

 

[roostracing]

Thick black wire goes to this connection then into firewall. That same wire seems like it may go to fuse box. There is a 2nd thick black wire w/yellow stripe that is near the fuse box but goes no where. Where does that wire go to?

 

[roostracing]

Just got done checking everything. Bronco wants to fire up. I checked inside the carb and no gas is being sprayed in. I put some gas into the carb and the bronco turns on. So I think everything is good to go once I install the new fuel pump. If everything starts up and runs, I then need to change the fuse I used to an oem style fusible link to get back to the low volts on the gauge....back to the original problem.

 

[DirtDonk]

Sorry. Had to go try out my other life for awhile!

When the fuse blew,I had absolutely no power what so ever in the bronco. No crank,no lights, no nothing.

That means that it definitely is not powering the voltage regulator. It's the main power feed for the entire truck, and during normal operation might work fine on a few amps. But during and especially right after startup, the amperage coming out of the alternator to re-charge the battery is way more than the fuse could handle.

Are all fusible links the same? Or ate there different ratings?I want to put one back in and take out the one I installed.

There are different ratings. For this purpose, Ford typically used a 14ga equivalent fusible-link. A replacement is available on the "HELP" racks at local parts stores with the part number 85623.
It's a pre-made section of wire with the ring-terminal and little tag on the end showing the rating, with a crimp connector at the other end ready to install.
I believe the general rule (if I remember) is 2 sizes under the working wire. So a 10ga wire would use a 14ga fusible link.

I am also going to install the carter pump tomorrow. Hopefully everything is back to normal. I will be using a relay. Obviously the relay will go to the battery but the other power source goes to any ignition source with key on only?

Yep, exactly. And with the relay's exciter wire only using a few tenths of an amp to activate, the stock ignition switch can handle that extra load no problem.
Depending on how far the main power run is, 14ga wire is considered the minimum. Most use that in their harnesses and it works just fine. But it doesn't hurt to use one size larger (12ga) if the pump is farther away from the relay and/or battery. That would only be for the battery-to-relay-to-pump circuit though. The relay to key would only need 16-18 ga wire to work just fine.

If it's a standard Bosch-type relay, then the connectors are like this:
1. Pin #30 = battery power to the relay.
2. Pin #87 = battery power to the load (pump in this case)
3. Pin #87A (if present) is not used in this case.
4. Pin #86 = Ground to nearest convenient spot.
5. Pin #85 = 12v in from the ignition switch.

Pins 85 and 86 are often interchangeable, but because some relays are equipped with diodes, it's probably a good idea to be consistent with whatever the manufacturer says. I may have remembered it wrong anyway.
Sorry if you already knew all that, but it's always worth re-mentioning here.

Are you going to rig up any kind of fuel-pump shutoff? Wouldn't be a bad idea to work one of those into the system at some point. Whether an oil-pressure activated switch, or something else, it's a good safety measure.

Paul

 

[DirtDonk]

Thick black wire goes to this connection then into firewall. That same wire seems like it may go to fuse box.

Definitely attaches to the fuse panel, or at least to a similar wire that feeds through the fuse panel.
This Black wire (black w/red on some models) is indeed the main power feed from the battery. It will go into the connector ('73 and later models) and then through the firewall, over to the driver's side (after feeding the fuse box and key and everything else) and back out to the passenger side firewall as a Black w/yellow wire of the same gauge. More on that below...

There is a 2nd thick black wire w/yellow stripe that is near the fuse box but goes no where. Where does that wire go to?

Where is that pic taken? Under the hood or under the dash?
That wire is the original charging wire from the alternator. Because it is literally the same wire as the all-Black wire (it's one big loop into the cabin and back out to the engine compartment) it's always hot when the battery is connected.
The one with the yellow strip is connected to the large "BAT" terminal/post with the red insulator on the back of the alternator. From there it feeds into the cabin, feeds all the branches of the system to power the accessories and fuse panel, and straight to the ammeter where it has a plug looking similar to the one in your pic. More of a short-n-fat version of it on the ones I'm familiar with. After it feeds through the inductive loop on the back of the ammeter, it becomes the Black wire then runs back out to the engine and starter relay where you've been playing around with things.
That's how the alternator charges the battery.

When the wiring is stock, any time that connector by the ammeter is disconnected, nothing will work. Nothing.
The voltage regulator does not require much current, so the Yellow 14 or 16 gauge wire is more than enough. One problem you have is that even though you have a replacement connector with all the correct wire locations, they're all Black so it's hard to know that you have the right wire spliced to the right wire on the regulator.

To check the regulator connections you can use a voltmeter to check these values:
1. F wire - no voltage when the engine is OFF
2. S wire - no voltage with the key OFF - Battery voltage with the key ON
3. A wire - full battery voltage all the time. Not just "12v" but full battery voltage. Any loss greater than say, a half-volt, can lead to incorrect charging. Maybe it's not quite that sensitive like I'm making it out to be, but I wanted to stress the importance of not having too much loss through the wires to the A circuit.

Not sure where else to go at the moment. Sounds like you're going to need to keep on digging to make sure that all the wires are not showing the same wear you found at the fusible link. They may have been overheated at some point, and though it did not quite blow the link in spectacular fashion, it's effected things enough to mess with your head.

Good luck

Paul

 

[roostracing]

Took old pump out already. I'm buying some self taping screws, fuel filter, hose, and clamps. The pump will be installed on the frame rail near the tank. Where is the best place for the relay? By the pump or under hood?