84 Bronco II Durapsark Conversion Help


JC1968

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Good evening,
I've just completed the duraspark conversion and am having a no start issue. I used the write up found here in the "How To" section and it was pretty straight forward so I'm sure all of my connections are correct.
Everything is new so I don't think it is faulty equipment. To be sure, I had my battery tested -->Good, ICM module tested-->Good and checked continuity between all of my connections --> Passed.
I had issues with the ignition switch in the past where the contacts were not touching so I had to press the two sections together and it would start with no issue. Maybe it finally crapped out, so I just replaced it also.
Before I did this swap the vehicle started with zero issue, I wanted to get rid of all of the emissions and vacuum garbage so I opted for the conversion.
One thing I have been noticing and have a question about (hopefully I can get a good answer, solution or way forward) a voltage reading I've been seeing regarding power to the coil. Of the two wires that come off of the grey 8 pin connector. The two listed in the write up are present (brown/pink and red/lt green). I tapped in to the red/lt green wire for coil power. When not connected to the coil, I get a 12 volt (battery match) reading. When I connect it to the POS of the coil it immediately drops to around 7 volts. Is this correct? I thought it would still maintain a 12 volt reading. Any ideas would be really helpful. Thanks in advance.

-JC
 


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franklin2

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You are probably reading through the resistance wire. I just did this swap also, but I used a HEI module. I had a no start after I did mine also, come to find out the coil connector decided to fall apart just as I did the swap. I am assuming you are using a new connector with a new duraspark II coil?

Do you have a testlight? If you do, clip it to a good ground, and then put the tip on the coil + and watch it during ignition on and during cranking. It should be lit in both modes. Then move the testlight to the negative of the coil. Keep the aligator clip on the good ground. Then crank the engine. The testlight should blink. If it's not blinking, the module is not turning the coil on and off.
 

JC1968

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I picked up the coil from a 79 mustang with the same engine off of RockAuto so I assume it's the correct coil. For the coil connector, this is the plastic adapter that attaches to both posts of the coil, correct? If so, yes this is also new. I don't have a test light but can pick one up tomorrow after work and give it a whirl. When testing the module, the guy mentioned to me I should also go with the HEI module instead but I figure if the ICM is good, might as well keep it. Maybe the HEI module will be a future buy if the duraspark module craps out.
Am I correct to say that the coil POS should be reading 12 volts though when the ignition is on?
 

franklin2

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I picked up the coil from a 79 mustang with the same engine off of RockAuto so I assume it's the correct coil. For the coil connector, this is the plastic adapter that attaches to both posts of the coil, correct? If so, yes this is also new. I don't have a test light but can pick one up tomorrow after work and give it a whirl. When testing the module, the guy mentioned to me I should also go with the HEI module instead but I figure if the ICM is good, might as well keep it. Maybe the HEI module will be a future buy if the duraspark module craps out.
Am I correct to say that the coil POS should be reading 12 volts though when the ignition is on?
You will not necessarily get 12v on the coil +. During cranking it's possible, though the starter zaps a lot of the voltage from the battery. During run the battery voltage is flowing through a resistor made into the harness. The coil does not get a full 12v in run mode in the original Duraspark II setup. Here is a diagram below of the duraspark II setup. It is from a larger pickup, but the wiring is very much the same on all the Fords, just the connectors may be a different number. You can see the resistor in the diagram, I have a 1984 Bronco II diagram and it's pretty much the same as the one below. About the HEI, the reason I used it was so I could use the square TFI coil and not have to use the resistor. Since you have already bought everything and have the correct coil, I would keep what you have.

 

ford4wd08

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You will not necessarily get 12v on the coil +. During cranking it's possible, though the starter zaps a lot of the voltage from the battery. During run the battery voltage is flowing through a resistor made into the harness. The coil does not get a full 12v in run mode in the original Duraspark II setup. Here is a diagram below of the duraspark II setup. It is from a larger pickup, but the wiring is very much the same on all the Fords, just the connectors may be a different number. You can see the resistor in the diagram, I have a 1984 Bronco II diagram and it's pretty much the same as the one below. About the HEI, the reason I used it was so I could use the square TFI coil and not have to use the resistor. Since you have already bought everything and have the correct coil, I would keep what you have.
This is why I chose to go with the HEI. I can keep my new TFI coil I just bought, mount it anyway I want, and deliver it the full 12 volts like the TFI system does.

I haven't done my swap yet, waiting on parts, but I plan on getting to it this weekend.
 

JC1968

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I see. I'm going to pick up a test light this afternoon and do the test listed above. I'll post back with my results. Hopefully I can find my issue soon.
 

franklin2

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This is why I chose to go with the HEI. I can keep my new TFI coil I just bought, mount it anyway I want, and deliver it the full 12 volts like the TFI system does.

I haven't done my swap yet, waiting on parts, but I plan on getting to it this weekend.
Just make sure you use two of the original harness wires for the power to the module and the coil. That makes sure you have power during cranking and during run positions of the key. You can see in the diagram above in the old duraspark II system they are separate, one wire has power during cranking, the other has power during run.

The diagram below is for a inline 300 six in a f150, but that system is very much like our original computer controlled carbed 2.8. In the diagram below you can see they have a blue-white jumper wire to tie those two power sources together for power to the TFI during start and run. You can see in the diagram below it still has the resistor, but they are not using it. The reason they did the wiring this way, is so they could run either type of ignition in the vehicle, with just one main harness.

What surprised me is when I got the 1984 diagrams, the Ranger and Bronco are wired the same way, and they also have the resistor in the harness. I didn't think the Ranger or Bronco ever ran a duraspark II system, but maybe they did in Canada or somewhere else. For whatever reason, its in there.

 

JC1968

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Update:
Bought a test light: placed on + of coil with ignition on -->lit, placed on + of coil while cranking -->lit, placed on - of coil while cranking -->blinking.
Also bought an in-line spark plug tester and placed it between the #1 spark plug and wire--> nothing. Thinking my wires are suspect or cap or rotor :unsure:. I really don't know.
quick video of me trying to start it. Maybe someone hears something I can't or can troubleshoot with the audio. anything helps.
https://www.youtube.com/watch?v=x4UQC_ugtHI
 

ford4wd08

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Just make sure you use two of the original harness wires for the power to the module and the coil. That makes sure you have power during cranking and during run positions of the key. You can see in the diagram above in the old duraspark II system they are separate, one wire has power during cranking, the other has power during run.

The diagram below is for a inline 300 six in a f150, but that system is very much like our original computer controlled carbed 2.8. In the diagram below you can see they have a blue-white jumper wire to tie those two power sources together for power to the TFI during start and run. You can see in the diagram below it still has the resistor, but they are not using it. The reason they did the wiring this way, is so they could run either type of ignition in the vehicle, with just one main harness.

What surprised me is when I got the 1984 diagrams, the Ranger and Bronco are wired the same way, and they also have the resistor in the harness. I didn't think the Ranger or Bronco ever ran a duraspark II system, but maybe they did in Canada or somewhere else. For whatever reason, its in there.

I believe the 4 cylinder Rangers might have come with duraspark system to begin with.

Mine is an '85, so the wiring is a little unique, but I plan on leaving as much of it original as I can.
 

franklin2

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Update:
Bought a test light: placed on + of coil with ignition on -->lit, placed on + of coil while cranking -->lit, placed on - of coil while cranking -->blinking.
Also bought an in-line spark plug tester and placed it between the #1 spark plug and wire--> nothing. Thinking my wires are suspect or cap or rotor :unsure:. I really don't know.
quick video of me trying to start it. Maybe someone hears something I can't or can troubleshoot with the audio. anything helps.
Your negative on the coil is blinking, so your module and the pickup in the distributor are working. Will your spark tester fit on the coil center wire? Or just take the wire off the center of the distributor and hold it close to something metal on the engine while someone cranks it and see if a spark jumps. If not, I would suspect something wrong with the coil.
 

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Have you pulled the distributor cap back off and checked the rotor and cap contacts? It sounds like the coil is OK, but the spark's not getting through the coil wire, rotor, cap, and plug wires. The spring tab on the rotor will usually show a mark from contact with the cap's center button, and make sure it's not bent down too much. If the parts were new, the rotor contact should show some small sign of the spark arcing, as will the cap contacts (these may show contact scratches, too). When I did my conversion the distributor used an adapter ring for the cap, and it seems that I had to pay attention that these parts were fitted together right. Your cap may be riding too high.
 

JC1968

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I did place a spark tester between the coil and distributor cap and did see light when I was cranking it. Reading RobbieD's post, I will be sure to check that my cap is not riding too high. I did question it but figured it should have fit properly. Thanks for the idea.
 

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What surprised me is when I got the 1984 diagrams, the Ranger and Bronco are wired the same way, and they also have the resistor in the harness. I didn't think the Ranger or Bronco ever ran a duraspark II system, but maybe they did in Canada or somewhere else. For whatever reason, its in there.
2.0 did until '88. 2.3 might have 83-84 (they went EFI in '85)

When you get it right it will work really well, I have no complaints about my Duraspark setup.

FWIW I did add a ceramic 3 ohm resister in the main power to the coil though (instead of the resistor wire)
 

JC1968

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Odd question, what is the difference between a Bosch distributor/rotor and not?
 


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