Duraspark to Points.

Discussion in 'General Automotive Questions' started by FordR500GT, Oct 8, 2017.

  1. FordR500GT

    FordR500GT In Maximum Overdrive

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    When my dad got his 75 f100, it came with a huge, jacked up mess of wiring and wouldn't run. After replacing the ignition switch, plugs, and fuses, I got it to run. Came back the next day so we could drive it around the block, and well ... no spark. It's been 3 years since it last ran, and I want to fix it up for my dad. We can't afford a new harness, and every time we buy them control module for it, it blows up and tests bad and the truck has no spark. New coil, ignition switch, ect. It's been such a hassle so I want to change it over to a points system. What does that involve? 390 2 bbl with no seat belt interlock madness. Any help would be appreciated....
     
  2. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Throwing parts at a problem, no matter if it's Duraspark modules or a points distributor, does not solve the problem. Anytime the wiring's a "huge, jacked up mess," your problem is not in the components, it's in the wiring. Who's to say you're not going to burn up your points and coil (or even start a wiring fire)? If you don't have the wherewithall to do wiring diagnosis, find someone who can. Make them a deal they can't refuse--a steak dinner with all the trimmings, or a rack of beer or even agree on a set dollar amount, and you buy what they tell you to buy. Just make sure you find someone who is honest and is a good worker. Now, IMHO, it sounds like someone has tied a wire in to the Duraspark primary wiring or has damaged it, and you have a dead short. This is just my opinion, but you need to begin with cleaning up that jacked up wiring before you do anything else.
     
  3. ribald1

    ribald1 In Maximum Overdrive PLATINUM MEMBER

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    Points are not more reliable than an electronic ignition, the opposite is true.
    Take the time to learn how the system works first. You very likely have already spent far more time trying to resolve issues than learning it would take.
    There are books, and there is the internet.
    Once you understand it, getting it to work reliably will be easy.
     
  4. FordR500GT

    FordR500GT In Maximum Overdrive

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    Well, regardless I will have to pull out the whole harness if I keep the duraspark. Some wires just aren't there anymore. I understand fairly well about duraspark systems and my dad pretty much knows everything there is to know. He worked on it for over a year replacing wires and connectors, but he is much too old to do that anymore, so I have no choice but to do it myself.
     
  5. aquartlow

    aquartlow In Maximum Overdrive

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    1st, double check your electrical grounds pertaining to ignition system just as a precaution. Was it possible the resistance wire to the coil was omitted and a "straight" 12V wire was run instead? 12V at coil is fine @ start-up/cranking but once running the action of the ignition switch causes the coil to receive about 7.5-9Vthrough the resistance wire, any higher and the Duraspark module WILL shut down and/or fry. Just a thought. Good luck.
     
  6. FordR500GT

    FordR500GT In Maximum Overdrive

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    I will look, but the duraspark system is factory, and everything that was cut and changed was under the dash
     
  7. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    That's where that resistor is--in the harness, under the dash, downstream from the column. It's 8-9 ohms, so by disconnecting the harness at the firewall under the hood, it would give you access to the terminal on that wire, then you go to the ignition switch connector, and do an ohm test for that wire. It's black with light green hash marks.
     
  8. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    By your original description, I missed that the wiring hassle was underdash, not underhood. But there could still be a dead short. Between that or the ballast resistor missing, those problems would wipe out a control module.
     
  9. FordR500GT

    FordR500GT In Maximum Overdrive

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    Oh good idea! I never thought about that!
     
  10. FordR500GT

    FordR500GT In Maximum Overdrive

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    What I don't get is that it ran once after we replaced the ign switch, now nothing. My dad changed the switch to a connector from an older truck, which was a bad idea.
     
  11. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Not necessarily. And a dead short in hanging wires could be intermittent, only touching when it wants to. But, do you have a u-pull-it yard near you?
     
  12. FordR500GT

    FordR500GT In Maximum Overdrive

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    My uncle has2 other parts trucks here. A 78 and 74
     
  13. aquartlow

    aquartlow In Maximum Overdrive

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    I "messed" around with my Duraspark ignition trying 4 different coils to find which worked best, I had bypassed the resistance wire and ran a 12v wire straight to a Ford TFI coil. It started and ran/idled really well, but when I put it in reverse/foot on brake pedal to back out of my warehouse my Ranchero quit running. I tried a couple of things to diagnose the problem then realized the 12v coil supply, upon touching the Duraspark module I found it fairly warm almost hot, it had shut down internally. I reinstalled a Duraspark type of coil(actually an MSD 2F coil) along with the factory resistance wire and everything worked as it should. IIRC, my '79 factory resistance wire colors were Red/Light Green stripe and has 1.1 ohm resistance. Hope this helps
     
  14. Basstrix

    Basstrix In Overdrive BRONZE MEMBER

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    Since multiple modules have failed, you have to look at wiring and correct module. Let's start by determining which module you should have. According to my brief search, a 1975 F100 with a 390 should have a module with a green strain relief. That's the color of plastic where the wires exit the module. So make sure that you have the correct module.

    Next, verify the wiring is correct. I've attached a diagram for the green module, so you need to verify the wires are correct on your harness.

    Resistance & voltage. Once you establish the wiring is correct, you need to measure coil resistance, check the pickup coil for continuity and make sure it's neither shorted or open. Follow the diagram and check appropriate wires for voltage when ignition is off, run, and start positions. My quick search didn't turn up the specific tests for the green module, but I'm sure if you google enough, you'll find them. DS Green.JPG IgnitionSystems_zps0cf8e2a7.jpg
     
    FordR500GT and 1965 Ranchero 66G like this.
  15. LSChero

    LSChero In Maximum Overdrive PLATINUM MEMBER

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    I installed duraspark II(blue) in my 72.Ran new hot lead with resistor in line,no issues.Lots of info on web.
    If you have to buy new module and resistor,maybe points setup would be cheaper way out.
    SAM_3827.JPG 76%20dura.jpg
     
  16. FordR500GT

    FordR500GT In Maximum Overdrive

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    Ok, I hooked up another coil I found, and I had spark. However, the spark was yellowish instead of blue. The truck fired up and ran for a few seconds before my battery died. Trying again tomorrow. Any reason for a weak spark? battery was fully charged when I started off testing for spark.
     
  17. ribald1

    ribald1 In Maximum Overdrive PLATINUM MEMBER

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    If it only ran a few seconds on a fully charged battery your battery AND charging system have problems.
    Low voltage will cause a weak spark, the ignition system wants over 13 volts while running.
     
  18. 1965 Ranchero 66G

    1965 Ranchero 66G In Maximum Overdrive PLATINUM MEMBER

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    Sounds like more than a few problems, time to start looking for the gremlin, the most obvious and most overlooked. Quit chasing and go back, take a deep breath and start over.
     
  19. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Yup, go right back to the basics.
     
  20. FordR500GT

    FordR500GT In Maximum Overdrive

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    Wouldnt doubt it is the connection between the solenoid and battery. All, the battery sucks and it takes a lot of power to crank the truck
     

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