Scout Died on the Freeway!

R

Richard

Member
77 SSII, 345 2bbl., 727 tf, headers, pertronix module, truetracs front and back.

I am hoping this is going to be an electrical/ignition problem. Scenario: it's 85 degrees today, I am on the freeway, I notice while going 65 mph a slight hesitation (like the Scout is starving for gas). I am off the freeway sitting at a light, temp gauge shows 190 degrees. All of a sudden, the Scout stutters and dies. I push it of to a side street, let it sit for a few minutes, try to start it, no go. It cranks over fine (brand new battery), and for a second it sounds like it wants to start right up, then not. Wait a few more minutes, try to start it, for about a second, sounds like it wants to start, then no go. Checked fuel, good squirt down the carb, check distro wires, all news (6months), coil seems to be rather warm.

While waiting for tow (about 45 minutes) try to start it, boom, starts right up. Temp gauge still shows bout 180 degrees. Let it sit at idle for a couple of minutes to see if it stumbles, it does, but then it smooths out.

Got back on the freeway, got back home (about 12 miles), got Scout in the driveway, turned it off. Let it sit for a few, then try to start it, starts up just fine.

So, this happened twice before over the last nine months and only in hot weather, never in cold weather. Its gotta be something electrical. Called pertronix help desk. Explained what happened. Techs thought was that it might be a wire that is heating up causing resistance and killing the juice to the disto. Or I am thinking the coil is getting toooo hot and maybe causing this problem. However, I had the same problem before and thinking it was the coil, changed it out. So back to a "weak" wire? Tech mentioned that the ignition switch hot lead might be the problem (but the switch is on the steering column), how would it heat up? I will research this (look at every wire) but I am open to suggestions. When looking at wires, what am I looking for?.
 
I would clean the heck out of the bulk head connectors. They are notorious for having intermittent problems. In particular the one with the main electrical wire from the alternator. Even if that's not it the connections are probably needing to be cleaned anyway.
 
This is just a pertronix to coil situation, right? No gold box anymore? You describe a classic gold box failure, that's why. Only other thing is to be sure the coil is matched properly to the pertronix. And obviously comb out all of the wiring and make sure there are no air gaps.
If none of that pans out and it still happens, try installing a small light connected to the + side of the coil. Mount the light in the cab, and if it sputters but the light stays solid, its not the wiring up to that point. Then you'd know it was the coil or the ignition module.
You're sure its not fuel, right?
 
Okay, update:

while at home: this is what I did:

+ cable to battery disconnected - volt meter shows 12.75 volts from + to disconnected cable. Connected - 12.75 volts.

At the alternator - with + cable of battery connected, b+ connection disconnected - 1.6 volts.

With the spade disconnected - one wire shows "0" volts,and the other shows 12.74 volts.

Then I took out all fuses as the fuse block. Disconnected + side of battery shows 12.75 volts. Not good!

With the battery conected + and -, b+ of alternateor shows 12.74 volts.

Something is definately not good. With the key off, I should get no reading at the alternator, right?

I am open for suggestions!! Help!
 
You should run the same tests with your meter but select dc amps on the 10 amp range, if you get no reading then on the 2 amp range. Using voltage can be missleading. And you should see no to a few milliamps (10-20) of currect max.

When you touch the b+ wire back to the stud can you see a tiny or any spark?
Can you put a small load across the b+ wire and the stud when disconnected? Like a parking light or 12 volt instrument/dash light. Then read the voltage or see if the light lights. I expect that you have a leaking diode in the alternator and the load will take out any normal reverse voltage leakage error. The meter (dvom) has such a high internal resistance (20meg) ohms that it May read the open circuit voltage even though the diode array should be stopping it.
 
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I got your private message about the alternator. I really don't know if this is an alternator problem still. It could be, but I am not sure, just reporting what I am getting when I read the vm. I thought that if/when you take off the + cable to the battery, there should be no volts anywhere unless there is a bad short/crossed wire. Am I wrong? Also, if all the fuses at the fuse block are out, there should be zero volts. This is very frustrating to me. I have had problems over the last two years with dead battery, charge them up only to drain again after a few days. It could very well be the alternator, I just don't know. This weekend, I will do some more searching, will unplug the ignition wire loom on steering column to see what shows. Very frustrating.
 
When you disconnected the positive battery cable you create a series circuit between the positive cable and any point on the vehicle that is in anyway connected to ground. The alternator in exactly that. The diodes are make that path.

Just so this post doesn't run amuck with improper testing methods and further confuse the issue, please follow my test methods perzactly. They will pinpoint your issue in the quickest time possible
 
I read you loud and clear. I will do the following:

1. With both battery cables connected, will test b+ wire off stud to see if there is juice.
2. With + cable off battery, same test for b+ wire.

I don't quite understand the Scout dying on the road though. My first thought is/was a bad wire shorting out (resistance)? I will also check ignition switch wire loom, upplug the clip and take readings. Very frustrating.
 
richard said:
I read you loud and clear. I will do the following:

1. With both battery cables connected, will test b+ wire off stud to see if there is juice.
2. With + cable off battery, same test for b+ wire.

I don't quite understand the Scout dying on the road though. My first thought is/was a bad wire shorting out (resistance)? I will also check ignition switch wire loom, upplug the clip and take readings. Very frustrating.
Click to expand...

I'm with you on the frustration level these problems create. Pinpointing the failure mode is in many cases a best geuss or theory one at a time. Simply takes time. The alternator could be your issue by either puting out a noisy dc voltage or even have an ac component to the power.
I think fixing the alternator first is a good approach here.

Start with your #1 bullet point and be sure to set the vom to amps not dc volts, along with the correct lead locations. Measure current flow between the b+ lead and the stud. Should be damn near 0.00. If so select the next smaller range.
 
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