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Discussion Starter · #1 ·
I've got a 351w, carbureted, with the EEC-IV ignition system. I am losing coils. As fast as 20 minutes or as long as a few days. Either way, i have replaced three or four over the last year. i don't run it very often. It has only been run for trips (in a truck that only makes dump runs.)

Any ideas? I've played with the idea of bad ballast resistor. Any other thoughts would be great.
 

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If it cranks but no start. A common failure on the EEC-IV was the TFI module at the base of the distributor. There was a recall on this back in the day. ask me how I know!
It just so happened to be a 84 351 with carb.
 

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Discussion Starter · #4 ·
TFI mod got replaced. I have tested coils and I know they are frying. Should I just replace the ballast resistor either way? Just in case?
 

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gijoe985 said:
TFI mod got replaced. I have tested coils and I know they are frying. Should I just replace the ballast resistor either way? Just in case?
Well, they can't be much money, so it couldn't hurt. Do the 84 EEC cars have them, or do they use a resistive wire? I imagine the resistor would be a wirewound type, which rarely drop in value (which is what would cause coil overheating).

If it has the four post starter solenoid on the fender, it's supposed to jump the resistor during cranking for more spark, and release for run to reduce ignition component stress. Perhaps the solenoid is keeping the ballast bypassed during run keeping the full battery voltage on the coil. Have you checked the temp of the coil after running 15 minutes or so?

John
 

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gijoe985 said:
After it is started, right?It should be 12v at cranking? What about when it is off and the key is in on position?
The voltage on the coil at cranking should be whatever the battery voltage is at that moment. If the battery voltage drops below 12 at cranking, that's what you should get at the coil. Once the car is running, the voltage should be lower than the battery voltage, about 8 volts or so as dropped across the ballast resistor.

As far as the car off and the key on, I don't think it's an important test. It's been a long time since I played with points, but if the points are open and there is no drain from the coil firing, then there will be an insignificant voltage drop across the resistor, and it will read roughly the battery voltage. If the points are closed at that moment, the voltge will be lower across the ballast resistor, prob about 8 volts or so.

John
 

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Discussion Starter · #10 ·
True or false-

My parts provider(whom is very knowledgeable) told me that the 84 EEC-IV didn't use an external ballast resistor.

Oh yeah, I just hooked up a new coil half an hour ago, turned the ky to the on position, walked around to the front of the truck to see what voltage I got, and I had quite a smoke show. Those smoke bombs I get for 4th of July have got nothing on my ignition coil... :p ;) :p :p ;)

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STATUS REPORT
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UPGRADED FROM ANGRY TO TEMPORARY INSANITY, LAUGHING: LAUGHING AT $50 SMOKING BEFORE MY EYES!
 

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Discussion Starter · #11 ·
Well I got another cool, replaced the voltage regulator. A guy told me that's what he'd seen do it before.

I think I need yet another coil.They kinda go out without warming. The wires going up to the coil were getting pretty hot.I didn't notice in time. It was all cool until I tried to set timing.

So the voltage is still at 12v once the truck is running. At the coil. I am assuming it is supposed to drop. Like mentioned above. What I hate is that this is something that Chilton's doesn't cover.

I was told there is no ballast resistor, but I foudn a "1984 F250 coil resistor" but is that on the EEC-IV system or on the duraspark? I think I'm going to just switch over to the duraspark system.
 

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Did you look into what John suggested about the 4 post solenoid being the cause? if you have 12V(battery voltage) at the coil when the key is in run mode and not start mode then check to see what's supplying the voltage. You already mentioned there not being a resistor wire so it must be the solenoid. Just picking up on what I've read here. I have never seen nor heard of this problem before. maybe the ignition switch is bad? just a guess.
 
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