77 bronco won't start w/ MSD atomic EFI/MSD Distributor/MSD 6al digital ignition

[jimnrenee's77EB]

Hey I need a bit of help. I have a 5.0 engine with original wiring with MSD atomic fuel injection. I am also running an explorer front serpentine. a couple months ago I removed the duraspark ignition and replaced it with a digital 6al. It had no problems actually ran better. then this last weekend I upgraded to a ready to run distributorwith adjust a cap to allow the EFI to control timing. throttle response increased and everything was great. the next day NOTHING. when you turn the key to start it does nothing. Any ideas?

Also I can jump it at the starter solenoid and it will start. I am just not sure why it will not crank from the key switch.

 

[TN1776]

First inclination is a bad ignition switch. If not that, then start tracing wires from the solenoid back to the ignition switch. The fact that it starts and runs when you jump the solenoid points in that direction.

 

[DirtDonk]

So literally nothing, as in no cranking of the starter either? What about interior switched stuff like the heater and headlights? Any joy there?

If nothing, then the main power wire from the starter relay to the interior could be the culprit. Since it's the original harness, there is a larger wire (about 10ga) on the battery side of the relay/solenoid thingy that provides power to everything. It has a fusible link section right there at the connector if it's original.
There is also a large push-connector right behind the instrument cluster in that same wire. Look near the ammeter to see if the two pieces have become separated. This will disconnect everything and not allow the power to get into the cabin switches.

Next is the ignition switch itself. Check that.

How is your Explorer alternator charge wire run? A heavy gauge wire directly to the battery? Or the original Black w/yellow 10ga wire?

Got some pics of the under hood area for us? Specifically the starter relay on the fender and the alternator area.

Thanks. Good luck.

Paul

 

[jimnrenee's77EB]

the only thing that happens when I turn the key is the fuel pump runs, the red light on the dash comes on and the airconditioner relay clicks. Thanks for your time and knowledge. yes no cranking of the starter.

 

[Joker11]

Another situation where I think it is just coincedence and not cause and effect.

I agree. Start at the solonoid and work your way back.

 

[DirtDonk]

Yep, those things you mention could very well be connected independently of the rest of the harness. Sounds like your main power source decided to take a vacation.

Things to inspect very closely would be:

1. Positive and negative battery cables.
This is more of a "just because" rather than being the most likely culprit. But they could still fool you easily if those other things that you could hear working are connected directly to the battery and not dependent on the main battery cables for their power.

2. The fusible link right there at the starter relay at the positive battery cable.
You might be able to test it with an ohm-meter if your harness has one of the 3-wire plugs upstream of it. Follow the Black wire up a few inches to see if there's a connector. If so, pull it apart and check for continuity.
If no connector, you may just have to get creative with your checking. But one visual check is whether the ring-terminal connector right there at the relay/solenoid is soft and mushy like it started to melt. If so, it likely gave it's life protecting something in your system.

Maybe a short, or maybe a more powerful alternator running through the old wires? That old stock wire can't handle the more powerful Exploder alternator, if that's how it's running.

Paul

 

[jimnrenee's77EB]

Paul, thanks for the help. I have been running the exploder alternator on the original wiring for about a year and maybe the fact that I have upgraded to the MSD ignition and distributor broke the camels back. anyways i was looking at the wiring schematic and I thought that the I terminal on the starter solenoid would be powered once the S terminal was energized. my replacement NAPA brand solenoid always has power to the I terminal. I replaced the ignition switch due to it being so old however it did no good. I was going to try to jumper the neutral safety switch but I used a test light and ran it through all of the positions and the light never came on on the S terminal to pull the relay down. Am I confused on how this works. THe red with green wire is on the s terminal and the black or brown wire is on the I terminal. my positive cable is on the left side and the starter is on the right side of the solenoid. I will try to get a photo up tomorrow but I have removed all of my exploder and accessories and still can't get the basic wiring understood.

Also none of the fusible liks are soft and mushy. I previously ran it according to the thread on Classic broncos as for hooking up the exploder wiring harness and it ran good. I am sure this is simple but I have started doubting what I thought I knew and now I can not find anything to back up either way.

 

[DirtDonk]

I have been running the exploder alternator on the original wiring for about a year and maybe the fact that I have upgraded to the MSD ignition and distributor broke the camels back.

Very possible. You've been living on borrowed time no matter what though.

Anyways i was looking at the wiring schematic and I thought that the I terminal on the starter solenoid would be powered once the S terminal was energized. my replacement NAPA brand solenoid always has power to the I terminal.

By "always" do you mean even with the key OFF? Or all the time when it's in RUN?
The "I" stud is normally only powered through the solenoid when the key is in START, but when the key is in RUN you can still read power through the Brown wire because that's connected to the ignition switch through the resistor wire. So while the stud should not be energized without the Brown wire there, if you were checking with the Brown wire connected, you'd see voltage feedback from the ignition coil circuit.

I replaced the ignition switch due to it being so old however it did no good.

Not a bad plan, as those switches do get old. But don't throw away the old one just yet. Now you have to see if the new one is bad! Actually, I'm only half-kidding with that comment. It's not unheard of for the new ones to be defective of course, but for now at least, read what I said above and see if that's how you were checking the I post. It might be perfectly normal operation.

I was going to try to jumper the neutral safety switch but I used a test light and ran it through all of the positions and the light never came on on the S terminal to pull the relay down. Am I confused on how this works.

Not necessarily. If you aren't getting power to the ignition switch, you're not going to get any signal to show on a test light no matter what position it's in. And the NSS is only going to stop the starter from working. It won't cut off power to anything else in the truck, so your power outage is not caused by the NSS.

The red with green wire is on the s terminal and the black or brown wire is on the I terminal.
my positive cable is on the left side and the starter is on the right side of the solenoid.

Correctomundo.

I will try to get a photo up tomorrow but I have removed all of my exploder and accessories and still can't get the basic wiring understood.

Be nice to see how it was wired, but none of the alternator wiring is likely to have caused your power outage, other than to have melted the big Black wire at some point. Still a direction to be looking, even without having found any funny feeling fusible links.
You're just going to have to test for resistance or voltage.

Perhaps a good place to start is with your test light at that connector I mentioned near the ammeter. When you pull it apart, one side should always have battery voltage. If not, your problem is still between it and the starter relay and the battery.
Use your light (a meter is better though, because it tells you stories about voltage losses, as well as just the fact that there is power) first on the battery side of the starter relay.
Then check for battery voltage at the other end of that wire, where it would have been connected to the post on the alternator.
Then find that 3-wire connector near the starter relay and check for voltage there.
If it's not at any of those places, you need to find out why. But at least you're hot on the trail.

Also none of the fusible liks are soft and mushy.

Well, that's a good first step, but unfortunately it's just looking for the obvious and doesn't mean that they aren't still bad. You need to follow that wire and see where the voltage stops flowing.

I previously ran it according to the thread on Classic broncos as for hooking up the exploder wiring harness and it ran good. I am sure this is simple but I have started doubting what I thought I knew and now I can not find anything to back up either way.

How was that? Through a separate heavy gauge charge wire straight to the battery/starter relay? Or still through the Black w/yellow charge wire from the original harness?

Did you inspect the Black wire near the ammeter? It's got a connector there that could have melted too, as it would be a source of possible resistance/heat and I've seen them melt there before.
If this had been a pre-71 I would have told you to check the two rectangular connectors on the firewall, but your '77 should not have those and the large Black charge wire should run straight through the firewall. It's only connections being at the starter relay, the alternator, and that one near the ammeter.

Maybe while you're playing with jumpers, run a small gauge wire (maybe 18 or smaller?) to the Yellow wire at the back of the ignition switch to see if you can get some of those accessories to work again.

good luck.

Paul

 

[jimnrenee's77EB]

Paul,

Thanks for your help, I am trying to get this back on the road for OCBR next week so I am starting to panic but if nothing else I will drag it there to get some assistance if I cannot get it figured out before then.

By "always" do you mean even with the key OFF? Or all the time when it's in RUN?

yes, with the key out and the S and I wire disconnected the I terminal has power.

Quote:
Originally Posted by jimnrenee's77EB
I previously ran it according to the thread on Classic broncos as for hooking up the exploder wiring harness and it ran good. I am sure this is simple but I have started doubting what I thought I knew and now I can not find anything to back up either way.

How was that? Through a separate heavy gauge charge wire straight to the battery/starter relay? Or still through the Black w/yellow charge wire from the original harness?

I used the black/yellow wire from the original wiring harness as the link below suggested. If I was to replace this wire what size should I use?

http://classicbroncos.com/tech/explorer-5-0-serpentine-accessory-drive-belt-conversion

 

[DirtDonk]

...yes, with the key out and the S and I wire disconnected the I terminal has power.

Ok, that's pretty easy then. Your starter relay is defective. The only possible explanation for power being on the "I" post with only the battery connected is that it's getting power from the battery. And the only time it's supposed to is when it's energized and the starter is spinning.
Sounds like it's time to take it back to see if it's under warranty.

I used the black/yellow wire from the original wiring harness as the link below suggested. If I was to replace this wire what size should I use?

Seems you missed that important bit in the article, and didn't see the mention of it in other places. It clearly says NOT to use your old wire and to replace it with a heavier gauge wire. And that your ammeter would no longer function because of it.
Just another reason to inspect that wire thoroughly throughout it's entire run, or just replace/bypass it to avoid questions. Either method will require some serious work on your part. But that brings us back to checking it to see if you can find an obvious break. Did you do that yet? It's a must on your part.

For this type of alternator, Ford uses either a 6ga or 4ga battery cable sized wire on their cars with this alternator. The size depends on the specific vehicle and is likely related to the overall length.
We sell a kit with 6ga cable and a mega-fuse here: http://www.wildhorses4x4.com/product/Battery_Charge_Cable_AMG_fused
You can make your own, or just buy a kit and mount it up. The cable runs from the main output stud of the alternator to the Mega-Fuse holder, then on to the battery or starter relay.
If you have room left on your relay's stud on the battery side, you might find it most convenient to mount it there with the other wires. If you're running out of room, it can go literally to the battery terminal on the positive side of the battery. Connect it to the nut and bolt and away you go.

Your old Black w/yellow alternator wire needs to be put away safely. The simplest is to take the end that used to be connected to the alternator and put it over there on the starter relay with all the other wires. If not that way, then you can cut the ring terminal off and cap it, tape it, tuck it away somewhere safe and don't worry about it for awhile.
If you choose the cut-it-off method, you can do it just about anywhere, but farther up the line inside the loom tape might be best.

You will still need the Black wire on the starter relay, but the Black w/yellow wire on the alternator is gone after that. And to get your power back you're going to need to inspect the Black wire at the starter relay. If I keep harping on that, it's because that's what's going to get you back on track. You can't avoid it because that's certainly appearing to be where your problem lies. Don't let it intimidate you into inaction, just yank it's chain until it reveals your answer.

Paul

 

[jimnrenee's77EB]

Paul,

Thanks again, I upgraded my starter solenoid to Napa's finest an ECHLIN and before I continued to troubleshoot my problem, I verified the "I" terminal was not getting power through the solenoid. which was awesome. Then I spent all night last night trying to figure it out and even found a spot where the wiring loom was split opne as if it were overheated however that was not fruitful. so I used a multimeter and discovered that the neutral safety switch stopping me from getting power to the red/blue "S" wire.

I misspoke a couple days ago, I used the Black wire and connected it to the starter solenoid and I made my own wires up for the alternator upgrade with a 175 mega fuse. However I did see your kit that WH offfers and I may be purchasing it just to clean it up a bit.

 

[DirtDonk]

...so I used a multimeter and discovered that the neutral safety switch stopping me from getting power to the red/blue "S" wire...

But I thought you said you didn't have any power?
Let's go back to square one. What works? You must have power to the ignition switch if you can get 12v to the Red w/blue wire in START.
Apparently there is power getting to the key, so what else is working? Can you turn on the headlights? The heater? Radio? Turn signals? That was what I asked in my first post, and I thought you said you had nothing?
If all of those other items work, then it's not the Black power wire.

...I misspoke a couple days ago, I used the Black wire and connected it to the starter solenoid and I made my own wires up for the alternator upgrade with a 175 mega fuse...

Well then with that news there doesn't seem to be any reason for the Black wire to burn out, so on to Plan-C
You said in your first post that when you jumped the starter relay you could get it to start. Did you mean just get the starter to spin, or is that with the key ON and a running engine?
If running, then we're chasing tails with the Black wire, because you have power to all the important circuits. If it was simply not getting power to the Red w/blue wire, then it sounds like finding the fault with the NSS is your problem maybe?
Is it running now?

Paul

 

[jimnrenee's77EB]

Paul,

yes after all was said and done the NSS was the problem however at the same time the starter solenoid was holding power and draining the battery,throwing a wrench in my troubleshooting. thank you for all of the advice, now I just have to put the rats nest of wiring back together.