Hey guys, awhile back I posted about having so much trouble marrying my engine and tranny together and you guys came through, I am super grateful for all of your help! The engine is now married to the tranny, everything is hooked up, looking as good as it can but I have now ran into a big of a snag. I will try to be as descriptive as possible, lay out everything I've done and hopefully get some insight...

The engine is a 351m/400 6.6L

My problem is no spark and I am almost sure this is centered around the distributor/ignition coil and it's wiring. At first I wasn't getting fuel so I thought that was the problem, a new fuel pump fixed that so now here we are. From what I've been reading on this site and others, compared to what my truck has... this has to do with how the ignition coil is wired. Problem is, while I think my harness is basically stock, the wire colors aren't adding up. I found the red/green wire that goes to the coil but no black wire for the other side of it. I've also heard about a "resistance wire" or "resistance ballast" but I don't know which one my truck has. I haven't located a pink wire that says "do not splice/cut" on it like some pictures I've seen so other than going off some schematics I've found online, I'm having trouble determining what to do. To ensure I don't have a component problem, I've replaced/added:

-New Pugs/Wires
-New Distributor
-New Ignition Coil (bluestreak)
-New ignition control module (old one had all the grease and back seal broken/leaked out)
-New Starter
-New Solenoid

SO, I guess with this info, my question is... first off how do I determine what year truck I have? The VIN on the door says I have a 77 with an automatic transmission but this truck is a 4x4 Ranger, 4 Speed so I can't trust it. Some people say I can look on the frame near the alternator (passenger side) but after a lot of cleaning, I haven't seen a VIN embossed or stamped. I buy parts for it like it's a 79 and all of them match what was in it so that's what I'm going with.

Secondly, does the red green wire go to the positive or negative side? The only wiring diagram I have shows the ignition coil but doesn't show the + or - on the diagram.

Third, why is it when I check the wire coming from my ignition (i think) it reads 12v (when turning the key) but when I plug it up, it drops to 5.6 volts? I'm guessing that has to do with the resistance wire? Most forums I've seen say 6-8 volts is what the wire will regulate the voltage to.

And finally... what damn color wires am I looking for? I know red/green is one but according to the only diagram I can find, it says I need a green/yellow? wire going to the ignition module. I'll link all pictures below and try to explain the situation. I'm sorry is this post is half autistic, my brain is scattered on why my coil isn't building any charge and I'm getting nothing on my timing light.

This is the WD I am going off of and I'm not even sure it's correct for my year. I did notice the green/yellow wire coming out the other side of the coil, but I can't locate that wire in my harness.

This is a photo I snapped when I was pulling the engine over a year ago. You can see a wire disconnected from the negative side of the IC, with a broken lead on the positive side, this is how I remembered which wire went to the negative... I think.

The wire with the really bad splice on the left is what was originally connected to the negative on my old IC. According to the wiring diagram I have, this is my red/green wire because it also connects to the "radio capacitor".

This is the mystery wire that I don't know if it goes to my ignition or not. I'm by myself working on this project but I can't identify it. It does read 12v when turning the ignition over to run (before trying to start) so I "think" it goes to the positive on my IC but I can't be sure. This also might be my engine temperature wire? Because that's the only wire I remember being broken and having a ****ty 90 degree splice to it.


Also a side note, ignore the really clean/new green wire coming out of my harness, that is a test wire for ground and nothing else I added it to the harness for testing.

If you guys need any other info such as resistance on wires or anything, please let me know and I will take the readings and get back to ya. Thank you so much for coming to my really bad TEDTalk.

 

The positive side of the coil wire makes its way to the ignition switch
The negative side of the coil wire goes over to the stator (pickup) in the distributor
But
Coil polarity is not critical, and the truck will run with a coil wired backwards
One way to tell if one is wired backwards
If you had an old scope that showed spark lines, the spark lines will be going down and not up on the oscilloscope
Using a test light, you need to verify the negative side of the coil wire blinks with the key on and the engine cranking
That verifies the integrity of the stator
One of these is indispensable when no spark testing on a Duraspark
I paid 40 bucks for one of these on Ebay

 

Thank you so much. So a little bit of an update, I found my missing yellow/green wire. It was buried in the harness with shrink wrap on it, which means I shrink wrapped it when I pulled the motor over a year ago to keep it from getting wet and forgot I put it in there. So now the coil is hooked up correctly, and I'm having a friend come over who can hold a test light while I try cranking to verify if I have spark or not. After hookling up the wires correctly, my truck did sputter like it wanted to start just for a moment so I'm assuming I finally have spark, but once my buddy gets here I'll know for sure and keep yall updated. I'm hoping this is just a timing thing now.

 

Okay an update. I am def getting spark now. Tested it by pulling a plug and resting it on the block so spark is confirmed. It looks like this might be a fuel issue now, I may have not rebuilt the carb correctly. Thank you for ur help.