All of the searches I did said that this a plug n play type ordeal. Everything does plug right in. I completely rebuilt the harness for the coil, ICM, and the Dizzy. All connections are good, and clean. I have power on the hot side of the coil, in run and start positions. I have power in the run position on the red wire out of the ICM, I have power in the crank position on the white wire out of the ICM, as was stated as correct in the manual. I tried the ICM off of the wife's truck, blue plug, same thing, it didn't work. I know the coil is good, I drove the truck in, same with the ignition switch. If we can't get power to the dizzy from the coil, doesn't that rule out the dizzy? The only spark I can get from the coil wire is when I let off of the key I get one spark. What gives?

 

If this is a Duraspark II, with the pickup coil in the distributor, and the 8-toothed reluctor wheel on the distributor shaft, I would check the pickup coil and the wiring from pickup coil to ignition module.

The fact that the ignition coil fires once on a key-off shows that the ignition coil, most of the ignition module, and power wiring are good.

Whenever I have had a no cranking or running spark situation on a Duraspark II, but had the key-off single spark, it was pickup coil related.

You could unplug the pickup coil connector and measure its resistance with a DVM. IIRC, something like 500 to 1000 ohms is good. If the pickup coil is bad, it will be an open circuit instead. The connectors I've seen have 3 pins - 2 pins for the pickup coil, and 1 pin for the shield. Want to measure across the two coil pins.

If the pickup coil resistance is good, and the wiring from pickup to ignition module is good, try a pickup voltage generation check. With pickup coil connector disconnected from the ignition module, put a DVM on a low voltage AC Volts (that's AC Volts, not DC Volts) range on the DVM on the pickup coil's connector pins. While somebody cranks the starter, the distributor shaft will turn, the reluctor wheel's teeth will pass by the core of the pickup coil. Each time a tooth passes the pickup coil's core, a low AC voltage pulse should be created. At cranking speed, it will look like a low AC voltage.

If you don't get any pulses, yet the pickup coil had good resistance in the earlier test, I would verify that the wheel's teeth come close by the pickup coil's core as it rotates.

 

We were suspecting the pick up coil. Needed more opinions, thank you.

 

Pickup coil did not fix the problem. Still no fire, except when you let off of the key. I am going out to do a closer inspection now. I really need to figure this out as this is my daily driver.

 

New symptom- if you pull the dist. out, it will arc like a key hot wire to ground. As it does this, it also creates a discharge from the coil, nice and blue. If you drag the dist. across metal (ground), it goes nuts creating good hot spark at the plug that I have in the coil wire for testing. In other words, the coil discharges repeatedly. The only thing hooked up to the distributor is the 3 wire plug, no cap at all. Also, we noticed that the "hot" I have at the coil in the run position seems a little weak. Any ideas? Better yet, are any of y'all as confused as I am?

 

That makes sense. The ground for the ignition module is really the black wire, that comes from the distributor via the 3-wire plug. In the distributor, the black wire is grounded to the distributor body by the screws that hold the cable grommet in the body. And when installed, the distributor is grounded to the engine, which in turn is connected to battery negative.

When everything is connected up, and you have key-ON, current is flowing from battery, through the ignition switch, through the Run resistance wire, to the Batt side of the coil, through the coil, over to the ignition module via the dark green wire, and the ignition module is providing a near-ground path for ignition coil primary current.

Then you come along and interrupt that current path, either via turning key-Off (removes battery power), or removing the distributor from the engine (removes ground). Either way, interrupting the coil current through the primary of the ignition coil causes the magnetic field in the coil to collapse, which induces a pulse of current in the secondary (sparks the sparkplug).

Dragging the distributor across grounded metal is just hooking up and then interrupting the primary current. Each disconnect will spark the coil once.

About the BATT side of coil... In START the coil gets full battery voltage via the start terminal of the ignition switch. But in RUN, the coil is fed battery through a resistor. In Fords, it's usually a resistance wire, a nichrome wire with a resistance of around 1 ohm. This limits current to the coil when running. So backtracking on the BATT terminal of coil, will find that there is a connection somewhere where the wire to the coil splits, one way via resistance wire to RUN position, the other via plain wire to the START position of ignition switch.

At the ignition module, going color by color for each ignition module wire, what do you have each one connected to? Or a web link that shows the circuit setup that you are using?

You do have the 8-tooth reluctor wheel on the distributor shaft, the shaft turns when cranking, and the reluctor teeth pass closely by the vertical center core of the pickup coil, right?

At one side of the base of the pickup coil assembly is a flat magnet. As each reluctor tooth passes by the pickup coil's core, it changes the magnetic field that the pickup coil is sitting in. This change in magnetic field creates the small pulse, that is then fed over to the ignition module via purple and orange (the color pair I've seen, anyway). The ignition module uses this to interrupt/reconnect primary coil current which fires the ignition coil.

 

Torky 2- everything you said makes perfect sense. At the module, I have-

Red- power in run
White- power in crank
Green- "ground", interruptor", "spout", whatever, the neg. side of the coil
Purple- signal from pick up coil
Orange- signal from pick up coil
Black - ignition system ground

One thing I feel I need to mention. Where the red and white wires go into the plug, they are flip flopped on the opposite side of the plug. So if you test the harness side, the red wire has power in crank, and the white has power in run. I checked the wife's truck, which runs fine, and they are the same exact way.

 

I fooled around with several durasparks even putting MSD hookups using the magnetic pickup distributor to trigger the MSD.

I guess I better dig out an old diagram to check on myself, but I have some doubts about the 3 wire dist wiring. I'm thinking that the dist should not cause a spark by making/removing contact with the block. Yes, it does collapse the field around the coil winding (transformer), which creates the spark, but the dist housing should not have any + battery potential on it with which to make or break any circuit and create a spark. I wonder if the pickup hot leeds are somehow grounded to the dist housing. I think the two other wires in the dist, besides the bk ground, are isolated all the way to the duraspark module.

There were some minor differences in the durasparks, depending on the color of the wiring strain relief. I guess the one you compared to is the same color as your new one.

Got my curiosity up anyway, guess I better start digging through some of my mess to find a diagram LOL !

 

At this point any and all help is greatly appreciated!

 

I had a problem like this on my 47 truck it has a 429/c6 I originally had the dura sparkII
and had it hooked up to a 12 volt coil ,It was my understanding at the time the duraspark ran 12 volts to the coil all the time however this may be wrong its possible that it may need a resistior even though I was using a 12 volt coil ,some coils have a internal resistor some have external resistor , but Iwas using a ford E-core coil that should take 12 volts all the time ?after about 20 minutes the coil failed so I bought a MSD blaster E core coil after about 20minutes again no spark. i check the coil ,the pickup dura spark with DVM everything looked good , I decided to change the duraspark to the MSD 6AL ,still no spark as it turns out the coil was bad even though you could get it to spark once as you decribed and it tested ohm wise per MSD .I bought a standard round MSD blaster II and its been running fine ever since.I guess what I'm saying is buy a new coil

 

The wrg diagrams I am looking at for the different configuration of Duraspark modules all show full 12V for cranking and a ballast resistor for the run side. I have used the 6AL with the MSD blaster coil and it requires a resistor as well.

The E-coil schematic does not show any resistor between the start/run sides, but that may be done internally. The system can detect if the engine is actually running by one of the tfi signals (~300 RPM) that is the same signal that tells the processor to power the fuel pump full time. I dont have a circuit description handy for the TFI so I cant be sure. Sooner or later, you will probably hear from someone who knows for sure!

 

You guys are all the greatest. After all the info you guys have given me, I almost understand the system now. Ford sure does some funky crap with wiring!

Anyway- a continuity test on the harness proved the orange wire connector to be bad in the plug to the dizz. Switched out the plug, beautiful blue spark! Cranked quite a bit dealing with a no fuel issue and PRESTO now I have a weak spark issue. Back to the garage.

 

I dont remember reading what this vehicle was originally. ???. Is it a processor controlled vehicle that originally had the TFI and was/is it a Fuel injected?

If it is, (most likely, with TFI) then you will have a problem with the fuel pump running. One of the signal wires from the TFI module (IDM/PIP ETC) was used to keep the fuel pump running. If it isnt connected right, the fuel pump will not get 12V needed to run continuiously.

 

This 85 Bronco is originally a California truck. Strike one, I know, but no rust! It has a single barrel carb, originally a feedback carb. Had a TFI system, now has the Duraspark II. The fuel pump is a manually operated pump. All emissions have been removed.

 

If you got it right, then it isnt a strike . No rust on anything is a big plus!

I have no experience with the feedback carb and how it operated. Brother and I looked at the VV's a little bit way back. None of it is really rocket science, and with a little description of its operation, most can figure it out. The TFI system for fuel injection includes a signal to the processor to turn on the fuel pump (IDM I think, which is the tach supply) when it detects the engine is running. If you have a manual pump, then you can troubleshoot it the old ways. Was it originally a manual pump, or was it converted? Also, was it a "feedback" carb or a Throttle body injection originally? Not trying to insult you, but are you sure its a feedback?

I had very good luck on Marine engines with a mallory unilight conversion and a blaster coil. Did away with those #### points! I used an MSD 6AL on an 85 TB 302 (306/comp 270M/holly projection) and triggered it with a duraspark style dist, worked well.


Guess I better dig around and see if I can find anything in my old Holly book or other stuff
LOL