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1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks Discuss the Early Eighties Bullnose Ford Truck

Help with Ignition wire

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Old Nov 12, 2021 | 08:48 PM
  #1  
Klenahan's Avatar
Klenahan
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Mountain Pass
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From: Pennsylvania
Help with Ignition wire

Hey, so I have an 85 f150 with a 4.9 and 4 speed. I did the Duraspark 2 swap this afternoon after finding out that the previous owner put a non feedback carb on, but nothing else. I have it all done, but it wont start. It fires, but only when in the start position. I believe my mistake was forgetting to connect the ignition run wire to the resistor. The issue I'm running into though is I can not figure out which wire I need to connect. Every wiring diagram I find online has it labeled as a Red and Green wire, but I cant seem to find one. Any help with where it is would be greatly appreciated, or there is something else I should be looking I would also appreciate that. Thanks
 
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Old Nov 12, 2021 | 11:50 PM
  #2  
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Surgemaster1277
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Joined: Jul 2018
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From: New York
Sounds like you need to tap a 12v voltage source that doesnt brown out when the keyswitch is turned back to the run position and the wire that feeds the 12v power from the start wire on the starter relay is eliminated.

I forget the pin # of the wire you can tap off of the ignition switch [not the keyswitch but in line of each other] on the column.




Its easy to determine the right power source wire you need...Disconnect wire on relay that allows engine to crank so engine doesnt crank unnecessarily and use a 12v wire probe to see which wire stays lit with key in run and crank modes and that is the correct 12v tap wire for the positive side of the coil...

You want to find something like this to tap the power from...





The resistor is just for radio noise and to eliminate electrical backfeed...

To eliminate rf noise I shrink wrap the ignition wires aswell as use ferrite chokes.........

 
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Old Nov 13, 2021 | 12:10 AM
  #3  
Klenahan's Avatar
Klenahan
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Mountain Pass
Joined: Feb 2021
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From: Pennsylvania
Yea, I ended up figuring out which of the old ignition coil wires was hot in the run position, and just used that. Thanks
 
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