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Coil gets HOT and engine cuts out. 1984 F250

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ArdWrknTrk

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

I remember you saying that, but you're the one that figured out that your ignition switch is bypassing the resistor wire.

So now we know that all these components have been putting up with a lot more current than they are designed for.

First let's fix the switch situation.
Gary pointed out that the wipers inside must have some overlap.
So either the detent needs to be stronger/deeper or the wipers need to be shorter in the overlap.
Or, a little of both

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

ArdWrknTrk

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

I'm going over to check if I have a gearshift for Shaun.
Maybe I have a spare ignition switch too.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Starliner

Re: Coil gets HOT and engine cuts out. 1984 F250

I grabbed yet another ign sw from the boneyard this week.

How about if I throw the ballast resistor in, it cant possibly hurt right?

The crazy thing is, this is pretty basic stuff. If I cant figure this out I deserve to stay home.

JOE
1984 F250 HD 2wd auto w/air,
351W, 2bbl, Dana 60 3.73, no EEC

ArdWrknTrk

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

I would say "it can't hurt"... but that's not fixing it.

That's like saying "my leg has a compound fracture. What if I just take some painkillers?"

Don't be frustrated.
It's exactly when something goes wrong with a 'foolproof' system that's functional for millions of others, that you need to be clearheaded.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Starliner

Re: Coil gets HOT and engine cuts out. 1984 F250

In reply to this post by ArdWrknTrk

I get a constant 10.7 V at pos terminal when running.

JOE
1984 F250 HD 2wd auto w/air,
351W, 2bbl, Dana 60 3.73, no EEC

Starliner

Re: Coil gets HOT and engine cuts out. 1984 F250

This post was updated on .

This is odd,
When idling the voltage to the coil is 10.5, but higher revs gives me higher voltage, past 12.
Maybe voltage regulator?

JOE
1984 F250 HD 2wd auto w/air,
351W, 2bbl, Dana 60 3.73, no EEC

Gary Lewis

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

That's easy to explain. When idling your alternator is basically not charging the battery so your voltage will probably be about 12.6. But when you rev the engine the alternator does charge and the voltage probably goes up to about 14.4.

Doing the math, 10.5 divided by 12.6 gives .8333. And 14.4 times .8333 = 12.0.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

ArdWrknTrk

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

A 1.1 ohm resistor would be dissipating 11-13A at those voltages!

No wonder it was getting hot when (Matt?) asked about the hot dash harness.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

Yep, which is why the ubiquitous Chrysler ballast resistor is ceramic.

Gary, AKA "Gary fellow": Profile

Starliner

Re: Coil gets HOT and engine cuts out. 1984 F250

In reply to this post by Gary Lewis

So do we do the ballast resistor, at least for now?

JOE
1984 F250 HD 2wd auto w/air,
351W, 2bbl, Dana 60 3.73, no EEC

ArdWrknTrk

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

As a bandaid, sure.

But remember, it gets hot.
Dodge mounted them directly to the firewall -as a heatsink-

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Starliner

Re: Coil gets HOT and engine cuts out. 1984 F250

Ah, ok bandaid it is just for now. I will continue to figure this out though, definitely haven't given up, not possible. Ibplan to measure coil temp at failure if or when. This WILL get fixed.

JOE
1984 F250 HD 2wd auto w/air,
351W, 2bbl, Dana 60 3.73, no EEC

ArdWrknTrk

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

A cheap IR non-contact thermometer is great for this kind of diagnosis.

But don't forget what I said about the symptoms being more a failing module, than a failing coil.

When coils die the ignition starts breaking up, and gets worse as long as it's running.
When the ignition module goes bad it just shuts off (or gives one backfire) before it does.

Transistors are binary, coils are not.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Starliner

Re: Coil gets HOT and engine cuts out. 1984 F250

Right, got it.
Honestly I am a bit lost as to where to start. Maybe bandaid, then figure out the detent issue, monitor coil behavior, maybe swap out another ign sw. , maybe put the old motorcraft Ign. Mod back in,

Reading your post more Jim, I think I hear you, I am overloading the ign. Mod. And the source of that overload is more the issue.
I know there is a posting for testing the mod.
I also understand how the failures can create a weak ling around and around the chain so really, the obvious first, key detent.

JOE
1984 F250 HD 2wd auto w/air,
351W, 2bbl, Dana 60 3.73, no EEC

Gary Lewis

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

Yes, it has to be something in the mechanical linkage that isn't causing the module to come back to Run.

I don't think there's a spring in the switch. It just slides. So all of the positioning is from the key tumbler and linkage.

As said, we see a lot of this in the winter when the grease sets up and doesn't let the linkage and switch come all of the way back to Run. What usually is witnessed is that the accessories don't come on, like the turn signals, clock, and radio. But the engine still runs.

I'd pull the tumbler and flush it out with cleaner and then lube it. And go through the linkage doing the same. Look for where it might be rubbing on something.

Gary, AKA "Gary fellow": Profile

old55pete

Re: Coil gets HOT and engine cuts out. 1984 F250

In reply to this post by Starliner

I was just talking to an older mechanic, Long story, and I have been following this thread from the beginning. For all intents and purpose, Im a heavy diesel guy and my shop has guys in it that also do light stuff too. I was explaining this thread to him(he used to work at Ford shops back in the day). He asked me if anyone had checked the pickup coil in the distributer ?

Just a thought.

Steve
86 Bronco, XLT, 5.0 EFI, EEC IV, AOD, IFS, limited slip front and rear, 3.08 gears, Tilt steering, factory AC

ArdWrknTrk

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

The pickup in the distributor CAN go bad (I've replaced them before)
But it's not going to cause -or fix- the ignition switch problem that is not connecting the resistor in series to the ignition coil.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

ArdWrknTrk

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

I'm pretty sure to have determined that the coil and module are having to sink too much power because the ignition switch is not fully returning from start to run.

If the pickup goes out the box does not break ground to the coil.
Another vexing ignition problem is if the tiny brass ground tab inside the distributor comes loose or breaks.
This is the only ground in the whole primary side of the ignition system.
The coil can't build flux if it's not grounded.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

ArdWrknTrk

Re: Coil gets HOT and engine cuts out. 1984 F250

Administrator

In reply to this post by Gary Lewis

Gary,
There's definitely detents in the switch.

Whether flat brass springs or a coil behind a ball, something causes the switch to assume distinct positions, no?

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

old55pete

Re: Coil gets HOT and engine cuts out. 1984 F250

In reply to this post by ArdWrknTrk

Sorry Jim, Dave went through the whole "how to adjust the ignition switch properly" off of the top of his head. Then commented on greasing the rod and cylinder/key. You guys had already covered that pretty well so I omited that, He did ask if the rod dident get accidently bent when the switch was changed, but as you guys had all of that covered, I left that out also. The only thing that hasent been said that addressed the original problem" coil gets hot and engine cuts out" was the pickup coil in the dist.

So at this point I will just step away and keep following.

Steve
86 Bronco, XLT, 5.0 EFI, EEC IV, AOD, IFS, limited slip front and rear, 3.08 gears, Tilt steering, factory AC

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