Dura-nospark

Discussion in 'Ranchero Tech Help' started by Jeff B., Jul 31, 2021.

  1. Jeff B.

    Jeff B. In Third Gear GOLD MEMBER

    Messages:
    150
    Location:
    Anacortes, WA
    I was taking ohm readings outside the distributor housing after it passes through the grommet and splits from 2 to 3 wires going into the vehicle harness. I had to cut the plug connector off the new pickup and splice it into the vehicle harness. I spliced with bullet connectors so can easily disconnect and reconnect them. That’s how I was able to read across both dark wires. It’s wired correctly. And I figured my decimal reading was due to the scale, thanks for confirming.

    I destroyed the original pickup by being careless with wire routing under the cap and letting the armature/reluctor catch one and tear it to shreds during initial startup after a spring change.

    I’ll dig into the article you sent. Thanks again!
     
  2. aquartlow

    aquartlow In Maximum Overdrive

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    You are very welcome. Hope you find the culprit of your Duraspark problems.
     
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  3. Jeff B.

    Jeff B. In Third Gear GOLD MEMBER

    Messages:
    150
    Location:
    Anacortes, WA
    So… I’m still chasing some of the same ignition problems. It’s a loooong story. If you’re interested check out this thread on ford-trucks.com. My username on that site is Go Seahawks!
    https://www.ford-trucks.com/forums/1670004-ignition-timing-problems.html

    I’ll post back when I have this problem child up and running again and a summary of what I’ve learned about the unique 1974-only Solid State ignition system (not DuraSpark 1 or 2).

    In the meantime does anyone here have any experience in replacing a resistance wire? The Ford Engine Service Manual describes a process of splicing a new one (Standard Motors p/n RW34, replaces OEM p/n COLF-12250-A) into a red/light green wire at the fuse panel under the drivers side dash at one end and under the hood at the other.

    I’ve never removed a fuse box from its base which is necessary according to the manual. Any hints? Also what are some visual characteristics of a resistance wire so I can recognize it to cut and isolate the old one?

    Thanks!
     
  4. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    12,133
    Location:
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    Well, basically, the resistor itself will be a bulge in the harness. If you can find which part of the harness that has that specific wire, you should be able to feel it, if not see it. Once you make the swap, rewrap the harness with black tape to protect it.
     
  5. Hillbilly

    Hillbilly In Maximum Overdrive

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    Location:
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    That resistance wire should be contained entirely in the in-dash harness. Should start very near the ignition switch plug-in then be folded up a few times before ending at the firewall bulkhead connection. There will be black tape covering the whole length of wire in the dash harness. All the resistance wires in the dash harness that I have seen had a black, probably asbestos, covering over most of the wire's length.
     
  6. Jeff B.

    Jeff B. In Third Gear GOLD MEMBER

    Messages:
    150
    Location:
    Anacortes, WA
    Thanks guys!
     
  7. burninbush

    burninbush In Maximum Overdrive

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    You can tell it's a 'resistance' wire by the way it feels; it is made from aluminum if I remember correctly. Feels very different from a copper wire.

    Are you sure that's the problem? I'd try running the car hot-wired first to see if that fixes the issue.
     
  8. Jeff B.

    Jeff B. In Third Gear GOLD MEMBER

    Messages:
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    Location:
    Anacortes, WA
    No I’m not sure. I am sure there is battery voltage at the + side of the coil when it should be resisted and between 4.9 and 6.6 volts. I’m also just as sure I’ve seen around 6 volts at the same point while I’ve been chasing a weird ignition issue. I’m going to start tracing the wiring back to the resistor wire to see if anything stands out like a loose connection.
     
  9. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    12,133
    Location:
    Seguin, TX
    The resistor is only 3.3 ohms, IIRC. So it should not be dropped that far down in voltage. And, also IIRC, electronic ignition won't operate below 8.5 volts, so something's dropping the voltage down. KOEO, fully-charged battery at 12.65 volts, the voltage at the ignition switch should be only dropped .5 to 1 volt.
     
  10. burninbush

    burninbush In Maximum Overdrive

    Messages:
    8,437
    Location:
    near SF
    Per my docs, the resistor is ~1 ohm (+/- a small fraction). If you have a multimeter, check the coil resistance, might have shorted a couple of turns.
     
  11. Jeff B.

    Jeff B. In Third Gear GOLD MEMBER

    Messages:
    150
    Location:
    Anacortes, WA
    Like I said this is a loooong story. The ignition system is Ford’s first foray into a system that doesn’t use points. It’s not DuraSpark 1 or 2. It is 1974-only Breakerless (B/L), also called solid state in some places. I have the 5 volume 1974 Ford Service Manual. The Engine manual provides a ton of information but there have been a lot of challenges. There is a 1.4 ohm, 5 foot resistor wire in the system that is supposed to feed between 4.9 and 6.6 volts to both the coil and the ignition control module. I’m getting battery voltage sometimes and around 6 volts at others. I’m going on the theory there is a loose connection at the junction of the battery feed to the resistor wire so will be tracing the wiring back from the coil to find that connector.
     
  12. Hillbilly

    Hillbilly In Maximum Overdrive

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    Location:
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    First Jeff, that 5 foot of resistance wire is folded up inside the dash harness, not under the hood. Second thing is it is primarily powered thru the ignition switch in the run position. Now the ringer = There is a jumper wire going from the inner fender mounted starter relay to the coil hot terminal intended to give the coil full voltage while cranking. I have seen those starter relays cause your problem even if they operate the starter correctly. Ringer number 2 = Some Fords acomplished the full coil voltage differently by using a wire from the ignition switch separate from the resistance wire to provide the juice while cranking. Ignition switch on that version can be the cause. Third cause could be a damaged wire harness from chafing on a sharp edge or having touched a hot surface. Gonna' take some searching.
     
  13. 1965 Ranchero 66G

    1965 Ranchero 66G In Maximum Overdrive Unubtanium Member

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    Just guessing but would a Pertronix distributor work.
     
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  14. Jeff B.

    Jeff B. In Third Gear GOLD MEMBER

    Messages:
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    Location:
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    It might but I’m so invested in this system I have to get it working. New dizzy, module and coil as well as HT leads and plugs.
     
  15. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

    Messages:
    12,133
    Location:
    Seguin, TX
    So, is this problem only at START, or both START and RUN?

    If during cranking, the starter should only pull battery voltage down to 10.5-11.5 volts, which should not affect the ignition during cranking. One thing you can try would be to run a jumper from battery positive to coil positive, battery positive to module input power, then crank the engine, see if that affects the ignition enough to make the engine catch, then run.
     
  16. Jeff B.

    Jeff B. In Third Gear GOLD MEMBER

    Messages:
    150
    Location:
    Anacortes, WA
    The immediate problem is there is battery voltage at the coil in Run. There are two separate circuits from the ignition switch to the coil: battery voltage for Start and then through a ballast resistor (wire) to drop voltage in Run. Both circuits run from the switch, through the ignition module, to the coil. The affect I’ve seen is the engine starts right up and throttles up nicely without vac advance connected. However it either dies immediately with manifold vacuum applied through the advance can, or misfires and threatens to die with ported vacuum when the throttle is cracked.

    This isn’t a unique problem. There are discussions on a number of online forums. The solution on every one I’ve read is replacing the stator due to a failed part (resistance out of the specified 400-800 ohms) affecting phasing. I replaced the stator 3 times before I discovered the voltage problem at the coil even though every stator tested for good resistance. The voltage problem at the coil has to be corrected before I can move forward, and in fact I expect (and hope!) this to be THE cause of the ignition problem.
     
  17. pmrphil

    pmrphil In Maximum Overdrive GOLD MEMBER

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    Have you tried to operate the vacuum advance with a Mityvac tool or something similar (I won't say suck on the hose :oops::rolleyes: but you get the idea)) while it's running WITH a timing light connected to verify it's not an advance issue? Like too much advance as if the stop pin is broken?
     
  18. Jeff B.

    Jeff B. In Third Gear GOLD MEMBER

    Messages:
    150
    Location:
    Anacortes, WA
    Yeah I have. When I apply ported vacuum with a Mityvac while having a timing light pointed at the balancer I see a big timing advancement jump at the same time the misfires start when the throttle is opened. I’ve tried adjusting the vac can and it affects the beginning RPM for the misfires which makes sense. The “looser’ the can is adjusted (higher sensitivity) the lower the RPM for vacuum to affect the can and timing.
     
  19. Jeff B.

    Jeff B. In Third Gear GOLD MEMBER

    Messages:
    150
    Location:
    Anacortes, WA
    My Ford shop manuals do not contain an engine wiring diagram for some odd reason. I’ve searched the web but have come up empty so far. The closest I’ve come are diagrams for 1972-1976 posted by 72GTVA in late 2009 BUT the diagram for 1974 is for a points system. Does anyone happen to have a 1974 solid state ignition engine wiring diagram? Thanks!
     
  20. Alan in Alabama

    Alan in Alabama In First Gear

    Messages:
    8
    Location:
    Alabama
    This diagram is from a Ford truck forum. It might be what you need.
    ignition diagram.jpg ignition diagram.jpg
     

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