Truck won't start with spout connected.

[genhawk21]

I have a Ford breakout box, so I would go about it a little different. Here’s some things I would check with the tools you have.
-Pull the SPOUT, start the engine, and test for power from the ECM side of the SPOUT connector. A digital multi meter will average the high and low voltage spikes on the SPOUT wire... you should see between 3-7 volts. (An analog meter will actually show you the voltage swings. You could even use a LED test light and see if it flashes.)

If you have 3-7 volts, your SPOUT is working correctly. You have 2 options: leave the SPOUT connector out or find an EEC-IV expert.

If you don’t have 3-7 volts, what do you have?
12 (or close) volts, you have a short to power. 0 (or close) volts you have a short to ground.

Snoranger -- I got 2.9v or 0v when attempting this.

Meanwhile, we peeled back some of the harness tape to see what the previous person(s) had been up to and found the mess below. Despite all the "repairs" the SPOUT pink wire is hooked up correctly in the sense that it goes from the PCM to the connector, and connector to the ICM (tested for continuity at least on both sides). We have a replacement SPOUT connector to wire in and clean up that mess, once we find the issue.

Meanwhile we are wondering about the bare (black) wire in the middle of the pic, which we believe comes from the rearward driver's side body ground, through the ICM shielding tape along with four other wires including the SPOUT wire, then through C124 behind the fuse box, and from there to.... maybe the CPS ground?? Despite being bare it seems to be a good ground, we can't imagine that there's supposed to be naked wire in the harness but we're not sure if it's related to this issue or not. I had previously checked the CPS ground wire at the connector and found it to be good.

 

[RonD]

Man that mess should just be taped up and let the next guy deal with it.....................oh wait you are the next guy

Sorry, couldn't resist

 

[genhawk21]

Man that mess should just be taped up and let the next guy deal with it.....................oh wait you are the next guy

Sorry, couldn't resist

Funny thing Ron, we are pretty close to slapping a momentary switch back on the SPOUT and forgetting about it. It runs really well if you put the SPOUT jumper back on after starting. It just seems like it ought to be fixable. Hate to give up...

Reading a little about how the shielding works -- seems like maybe that bare wire should go around the outside of the shielded bundle, not inside? Maybe someone undid the foil tape and put it back wrong? I doesn't look disturbed though. Ugh.

 

[RonD]

The SPOUT is the "Vacuum advance" on this system
If you were to apply 18" of vacuum to vacuum advance distributor and try to start engine it would be hard to start
Cranking engine only makes about 4"-5" of vacuum, so base spark timing is used, 10-12deg BTDC

So SPOUT could be causing its regular 10deg advance, engine running, but doing it at key on so cranking is at 20-22deg instead of at 10-12deg

Disconnecting SPOUT allows base spark timing for start up, and then reconnecting SPOUT adds the advance needed for operation

Why, don't know

You could hook a 5 post relay to SPOUT, pins 30 and 87A are the two SPOUT wires
Then activate the relay with the "S" wire, red/blue wire, Starter activation wire on starter relay on inner fender
So when cranking starter motor, SPOUT is disconnected, once starter is off SPOUT is reconnected

Automatic disconnect and connect

http://www.gtsparkplugs.com/images/mini-automotive-relay-wiring-840x.jpg

30 and 87A are connected when relay is off, so most of the time SPOUT is connected
When activated(by starter motor) 30 and 87A are disconnected

 

[Snoranger]

Snoranger -- I got 2.9v or 0v when attempting this.

Meanwhile, we peeled back some of the harness tape to see what the previous person(s) had been up to and found the mess below. Despite all the "repairs" the SPOUT pink wire is hooked up correctly in the sense that it goes from the PCM to the connector, and connector to the ICM (tested for continuity at least on both sides). We have a replacement SPOUT connector to wire in and clean up that mess, once we find the issue.

Meanwhile we are wondering about the bare (black) wire in the middle of the pic, which we believe comes from the rearward driver's side body ground, through the ICM shielding tape along with four other wires including the SPOUT wire, then through C124 behind the fuse box, and from there to.... maybe the CPS ground?? Despite being bare it seems to be a good ground, we can't imagine that there's supposed to be naked wire in the harness but we're not sure if it's related to this issue or not. I had previously checked the CPS ground wire at the connector and found it to be good.

View attachment 75470

2.9 volts is at the low end but that may just because you were testing at idle. The more advance the ECM calls for, the faster it would pulse and you would see higher voltage.
You would only be concerned with the wire between the ECM and the SPOUT connector... the problem only exists when the SPOUT is plugged in.
The bare wire is normal. That’s the RF shield wire.

I would disconnect the ECM and test the SPOUT wire for continuity to both power and ground. You shouldn’t have any. If that checks out ok, I’d check for continuity between every wire in the ECM connector... it should only have continuity with the 1 pin for the SPOUT.

 

[genhawk21]

The SPOUT is the "Vacuum advance" on this system
If you were to apply 18" of vacuum to vacuum advance distributor and try to start engine it would be hard to start
Cranking engine only makes about 4"-5" of vacuum, so base spark time is used

So SPOUT could be causing its regular 10-12deg advance, engine running, but doing it at key on so cranking is at 20-22deg instead of at 10-12deg

Disconnecting SPOUT allows base spark timing, for start up and then reconnecting SPOUT adds the advance needed for operation

Why, don't know

If I'm understanding you right that would mean it's getting a SPOUT signal on startup when it shouldn't be? I'm so confused at this point lol.

 

[Snoranger]

You can also put everything back together and test the IDM wire. It should have the same voltage as the SPOUT.
SPOUT is the signal from the ECM and IDM is the return from the DIS module. It’s purpose to to let the ECM know that the ICM is adjusting the timing to where the ECM wants it. Think of it as “SPOUT is the shout, IDM is the echo”.

 

[genhawk21]

2.9 volts is at the low end but that may just because you were testing at idle. The more advance the ECM calls for, the faster it would pulse and you would see higher voltage.
You would only be concerned with the wire between the ECM and the SPOUT connector... the problem only exists when the SPOUT is plugged in.
The bare wire is normal. That’s the RF shield wire.

I would disconnect the ECM and test the SPOUT wire for continuity to both power and ground. You shouldn’t have any. If that checks out ok, I’d check for continuity between every wire in the ECM connector... it should only have continuity with the 1 pin for the SPOUT.

Thanks Sno. I'll try that all tomorrow and report back. At least I'm learning a lot from all this. Didn't know about how shielded wires worked until today!

 

[RonD]

If I'm understanding you right that would mean it's getting a SPOUT signal on startup when it shouldn't be? I'm so confused at this point lol.

Yes, ICM or computer is causing 10deg spark advance when cranking engine over, because SPOUT is connected

I added to my above post about installing a relay to disconnect and reconnect SPOUT automatically
It is "kicking the can down the road", if it works, but its also easy to remove if you find the problem

 

[genhawk21]

I added to my post about installing a relay to disconnect and reconnect SPOUT automatically

I saw that, fantastic idea!! I think Rangersblenger (whose truck it actually is) like the idea of a switch as an anti-theft measure. It's certainly very effective.

But your relay idea is much cooler.

 

[genhawk21]

2.9 volts is at the low end but that may just because you were testing at idle. The more advance the ECM calls for, the faster it would pulse and you would see higher voltage.
You would only be concerned with the wire between the ECM and the SPOUT connector... the problem only exists when the SPOUT is plugged in.
The bare wire is normal. That’s the RF shield wire.

I would disconnect the ECM and test the SPOUT wire for continuity to both power and ground. You shouldn’t have any. If that checks out ok, I’d check for continuity between every wire in the ECM connector... it should only have continuity with the 1 pin for the SPOUT.

Snoranger (and everyone else) -- here are the results of testing (I didn't get to it yesterday).

Test #1: Retested SPOUT to ECM, running with SPOUT disconnected = 11v, drops to about 6v with throttle up

Test #2: IDM (pin 12, bottom outboard of ICM) while running with SPOUT disconnected= 6.6v and with SPOUT connected = 11v drops to about 6v with throttle

Test #3: Tested SPOUT (pin 36) at ECM connector for ground and power with a test light, nothing with engine off or KOEO (wasn't sure if that mattered)

Test #4: Checked spout wire for continuity to every pin in the ECM, only drops to 0 ohms for pin 36

Test #5: I retested the TPS based on a comment from another forum, it tested good output again (I tested it previously). I don't have an analog meter so I can't be sure it has a smooth response. But I don't think it's causing a no-start in any way.

I won't pretend I understand most of this so hopefully you can help me out. The 11v on Tests 1&2 seems high but it does change with idle and the SPOUT out (is that redundant?) and the IDM do mirror each other. So it's doing something. Test 3&4 everything is as it should be if I understand correctly.

I really appreciate all of you taking the time to help me with this, and how much I'm learning from going through this. Today, for example, I learned that there are quite a few blanks in the ECU connector! Startled me when I hit the first one with the probe lol.

I've been wanting to get better at diagnosis and electrical for a long time, so I suppose I should be grateful to this frustrating issue for forcing me to work on that.

 

[RonD]

That's why many people say they liked "the good ol' days" with carbs and points because they knew how to work on them if there was a problem

But the REASON they knew how to work on them was because THEY HAD TO WORK ON THEM ALL THE TIME just to keep them tuned up

The reason they don't know how to work on the computer/electronic systems is because they rarely have problems and don't need the attention the vehicles from "the good ol' days" needed, constantly, lol

 

[genhawk21]

Good point Ron! I "inherited" some old time points tools and other mysterious (to me) auto stuff from a very elderly neighbor who gave them away before moving in with his kids after his wife died. It felt very weird to take tools from him but he was happy they would get used (and I do use quite few). Maybe one day I'll pick up a "classic" and find out what that stuff is for.

 

[Snoranger]

So the SPOUT and the IDM have a matching signal. That’s good. It sounds like they’re either getting the wrong signal or the base timing is off.
I don’t know how to test the signal. I may be able to find it, but you’re probably going to need a scope to see it.
If the ECM is sending the wrong signal, it’s probably because another sensor is lying to the ECM. The output is only as good as its inputs. Let me do a little research and see what I can find.

 

[alwaysFlOoReD]

Good point Ron! I "inherited" some old time points tools and other mysterious (to me) auto stuff from a very elderly neighbor who gave them away before moving in with his kids after his wife died. It felt very weird to take tools from him but he was happy they would get used (and I do use quite few). Maybe one day I'll pick up a "classic" and find out what that stuff is for.

I went to a yard sale for a bbq. Ended up going back twice with my 20' flat deck to haul away two loads of lawn tractors and various parts and tools that were in a large dumpster or about to go in. The owners had died and the son was from out of province and didnt have time to deal with the stuff. I gave him $200 for it all and probably made ten times that over the next couple years. Most of the tools I still have and I think of the old gent every time I use one of his tools. It's sad. And that is probably what will happen to my stuff as I have no one interested in mechanics to pass the tools onto. Oh well, once I'm dead I wont be worried about it any....lol.