I am curious what you may know about the Ford Duraspark III ignition system. I am having a bitch of a time with my truck's 460.
I am not getting spark from the coil, I have replaced the coil, (even though the old one show's good voltage and resistance in the primary and secondary readings,)
I checked all the connections, continuity on all ignition wires, the stator assembly(pick-ups) in the distributor showed up no good in tests, so I replaced that, it ran for a few miles and powered out, no sign of spark, after checking everything, doing really nothing, maybe just when it cooled down, I was able to drive it home. It ran fine, started no problem, I drove it around till it was good and hot drove it home, parked it, it started again, even after a couple hours. brought it too operating temp, shut it off started it, no problem.
This morning, after the block heater had warmed it, and my battery was charged fully over night, turns over no problem,it won't start, no spark,
I brought the ignition module in and it passed all inspection tests, I replaced the EEC-III voltage regulator today to eliminate that possibility, still won't spark.

I have:
- good wires continuity from distributor and alternator to module etc.
-new regulator (EEC III micro-processor)
-good module (according to a proper module tester at a service garage)
-new coil (good coil wire too)
-new stator assembly
-AND NO SPARK OFF THE COIL,

It , starts first turn when it fires, runs periodically a short while, dies instantly, won't spark again until it feels like it, what is wrong here?????

I also have, just for the record,
-shiny contacts on sprocket on distributor shaft
-shiny clean distributor cap and rotor contacts
-clean plugs on harnesses, and tight clean wire contacts throughout
- new vacuum advance control on distributor
-good sparkplugs and wires
-new starter solenoid


If you know anything feel free to fill me in


Michael Hedican
The Bobcat Guy
e: Mike@BobcatGuy.com
t: 604.783.8627
f: 604.930.1132

 

Copied directly from an auto parts store site. Not sure if it will help but it struck me as odd.

DURASPARK OPERATION

With the ignition switch ON, the primary circuit is on and the ignition coil is energized. When the armature spokes approach the magnetic pickup coil assembly, they induce the voltage which tells the amplifier module to turn the coil primary current off. A timing circuit in the amplifier module will turn the current on again after the coil field has collapsed. When the current is on, it flows from the battery through the ignition switch, the primary windings of the ignition coil, and through the amplifier module circuits to ground. When the current is off, the magnetic field in the ignition coil is allowed to collapse, inducing a high voltage into the coil's secondary windings. High voltage is produced each time the field is thus built and collapsed. When DuraSpark is used in conjunction with the EEC (DuraSpark III), the EEC computer tells the DuraSpark module when to turn the coil primary current off or on. In this case, the armature position is only a reference signal of engine timing, used by the EEC computer (in combination with other reference signals) to determine optimum ignition spark timing.
The high voltage flows through the ignition coil high tension lead to the distributor cap where the rotor distributes it to one of the cap terminals. This process is repeated for every power stroke of the engine.

Ignition system troubles are caused by a failure in the primary and/or the secondary circuit, incorrect ignition timing or incorrect distributor advance. Circuit failures may be caused by shorts, corroded or dirty terminals, loose connections, unsound wire insulation, a defective pick-up coil assembly or amplifier module, a cracked distributor cap/rotor, or fouled spark plugs.

 

Thanks airharley, I am thinking one of my wires may have a fusible link or just be really corrodded internally, maybe causing it to lose continuity when running hot. I may run a new wire directly off of my battery to my coil too see if that helps, as I have tested and or replaced all of the other components you've mentioned. If that doesn't help I will try jumping the ignition and ballast etc. something has to work, and it better be soon, before I use a match to fix it for good!

 

Bob you can use a heat gun to simulate a running engine on the wires. That will help with the continuity test. We have to do that once in a while with the aircraft I work on. It's a pain but you know for sure.