Frying Petronix ignition pick-up coils

[colnago]

When I installed my Pertronix last year, I had to bypass the ballast resistor wire underneath the dash. As I recall, it was a heavier wire, and I think the wire housing even had the word "ballast" printed on the plastic. I know I found the wiring schematics for it in the tech section on this forum. Also, if you used a yellow coil, it was probably an Accel unit, because yellow seems to be "their color". I was told to stay away from the Accel stuff, since it's not as reliable as some of the others.

I've not had any problems with the Pertronix stuff, once I got it working, but it's not a daily driver either.

Joseph

[Bob]

Well I resisted the temptation to take this truck to the shop and finally decided to take a hard look at it and see if I could figure out what was going on.

There were / are two issues. First off turns out the way I was checking voltage at the coil was apparently a dwell reading. (I'm told?) I was putting the red on the coil plus and the black on the coil minus. That's why the low reading there. So I checked it with the ground to the frame and it was varying every time I poked at it. I checked my ground and it was good. Pulled the plug at the firewall and still funky varying readings. Decided to try putting a new ignition switch in. Put it in and got 12.4 at the plug. Yeee haa I said to myself... Checked it again to make me feel good and son of a gun if i could get a solid reading again. It was going all over the place. Pulled the switch again and got to looking at the plug that goes into it. When I pushed it on and off the thing it wasn't very tight. Took my pen knife and poked around in all the female slot connectors then got the blade behind them and bent them in a little so they'd grab better. Now when i pushed the plug on it felt nice and tight.

Checked the voltage of the red with purple stripe hole at the plug coming out of the firewall again and again and again and one more time. Turned the key off and on a few times and checked it several more times and EVERY time a nice SOLID 12.4 volts. Tah Dah... So I thought...

Plug the wire in that goes to the coil and checked the voltage at the coil and it's only about 6 - 6.8 range and varying a little. Crispy wire syndrome...

I'm guessing this is what has been causing the pick-up coils to fail and I'm betting that at least one of the few is probably actually O.K. The one that fried when my ignition switch went and wouldn't shut the truck off was visibly burnt looking. These others don't look that way and I'm guessing it could've just been a fluke that when I changed them it fired up. Just the right wiggle or whatever on the switch or crispy wire.

So rather than splice the wire I put a part request here to see if any of you guys have that piece of the wiring in good shape you can sell me. figured if I can find a clean one aand use the plug it'd be nicer than splicing. Not like a soldered splice would be a bad thing but plug would be nicer. Need the flat three prong piece that runs to the coil and temp and oil. If you have one let me know how much to send it to 15074

Thanks for all the help and input!
Bob

[70_F100]

That harness is avaiable from one of the Mustang parts places, possibly Mustangs Unlimited.

I know Robroy got one, so maybe he'll chime in here. You could always send him a PM.

[Bob]

Yep they had it and I have one on the way...!

Thanks!!

Never thought of trying to find a new one...!

[Bob]

Thought I'd update folks on this mess...
Got the new wiring piece in and it didn't cure my problem. On a couple of occasions when it died it seemed as though it ran out of gas. Also had what I thought was a lifter starting to tick. Bought a new fuel pump thinking maybe it was a fuel thing and low and behold turns out the pump fulcrum point in the casting was broken and the rocker pin had the casting all wallowed out. Wasn't getting anywhere near a full stroke from the pump.

Put the new pump in and figured I was cured. The ticking went away also... wasn't a lifter going it was the pump. Take off and it still died off and on pretty much randomly. Feeling real good that it's not a fuel issue anymore but sure it was a player in the game off and on before. Cleaned up more connections and put a new voltage regulator in and still no good.

Gave up and took it to the shop.

They ran both a hot and ground straight to the distributor and checked for spark and it was only on occasion. Picked up on the magnetic ring thing and it worked every time. Shimmed the ring thing up and seemed like all would be good. Wasn't... Pick up on shaft and rotate and no spark. The 1/4" of endplay on the shaft seems to be the issue. Probably orbiting some too. Apparently the magnets in the plastic ring that the pick up coil swings by don't have a very big window. Also guessing with the angle of the cut of the drive gear it probably lifts the distibutor shaft when running. Low rpms it could die because the ring was too low to see magnets and high rpm too high when it lifts.

Ordered a new distributor yesterday. Got the "Plug-n-Play Ignitor II" and expect this'll do the trick.

[1972hiboy]

ive enjoyed keeping up with this thread, very handy info being thrown out there.

[colnago]

Apparently the magnets in the plastic ring that the pick up coil swings by don't have a very big window.

I ran into the same problem when I installed my Pertronix. If you follow the directions, you end up pushing the ring all the way to the bottom of the distributor shaft. On my distributor, this made it too low for the magnets to be picked up. I had to raise it so the top of the ring was level with the top of the pickup. After that, no problems. On some other forum, I ran into a post where someone used a rubber hose washer underneath the magnet ring to keep it in place. I haven't needed one (yet); so far, the ring is staying in place on its own.

Hope your new distributor works out. Keep us posted.

Joseph

[Hawkrod]

Well now I'm just about as confused as can be.

When I installed a Petronix in my red truck (66) it ran fine until I got the rpms up then it'd start breaking up. Took it to a shop down the road and he said... "Oh... you just need to bypass that ?? thing ?? on the firewall." Said you couldn't utilize that "thing" when running electronic. All three of my current trucks have that thing on the firewall and all now have Petronix and none are hooked up to whatever that thing is.

Are you sure that wire you're talking about isn't the fuse link they put in? I really feel pretty sure that that thingy on the firewall is a resistor and the funny wire is a fuse? If I'm not mistaking I think there's a fuse link wire from the starter relay to the alternator too? Usually has a little box looking chunk molded into the wire.

Here nor there I suppose cause I'm gonna drop the green one (72) off later today to a shop and let them figure it out. I'm screaming uncle.

Appreciate all the input and I'll let everyone know what he figures the problem is / hopefully "was."

Sorry I have not responded back sooner but yes I am absolutely certain of what I wrote. Ford did not use an external ignition resistor in those years, they used an ignition resistor wire that runs from the ignition switch wire (it has an external plug on the harness so it can be replaced if it burns). The wire is a pinkish color and the isulation is very rubbery and is a couple of feet long. Your mention of a fusible link which is an entirely different component and is not used on the ignition circuit. If your trucks all have an external resistor then you have trucks that have been modified because they did not come that way. Are you sure you are talking about an external resistor? They are white ceramic with a connector at each end (see the pcture below). Hawkrod

Ignition resistor:

[Bob]

ive enjoyed keeping up with this thread, very handy info being thrown out there.

The popcorn eating smiley cracks me up...!

for all the years I've owned htis truck... maybe around 6...? It has had the Petronics conversion and all the while the resistor wire was feeding it. It handled it fine up until the day that my ignition went and then apparently it cooked part of that pink resistor wire somewhere just enough to run... sometimes.

The garage messed around a good bit and then after a new distributor all was good except it'd still die. So once again they ran a seperate wire to the coil and all seemed good. So they added a toggle to my dash and Voila!!

But wait... I get halfway home and the dash is smoking. The resistor wire is melting...

So I'm trying to figure out where this other wire it joins up with goes and I recall that I had a ... mostly complete... tear out wiring harness I had bought a few years ago for parts. So I lay it out on the tailgate and see that the pink resistor wire joins the brown wire at the three prong plug.... then goes over to the starter solenoid. Hmmmm

So I think about it and throw a meter on my battery. I disconnect the brown wire on the right prong in front of the solenoid and Voila...!! (for real this time...)

Turns out... If I'd have just run a new wire off the ignition switch as I was told straight out to the coil all would've been good... Except for the distributor being shot and the broken fuel pump...

Anywho... Been driving it for a week or two and all is good again.

[basketcase0302]