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Engine Stops Running, But Refires if Switch Recycled (off/on)

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MarkThomas

Engine Stops Running, But Refires if Switch Recycled (off/on)

My '86 F250HD 5.0L EFI runs great. Just finished a pile of replacements and fixes to get it running right. This morning, drive in to work, it stops running all at once. I turned the key off, then back on, she fires right up no issue. At lunch it did it again - same remedy. WTH?

She has a brand new Distributor with all new fire. I've tested the fuel pressure and it's within the specifications in Chiltens. Most of the sensors/regulators have been replaced - MAP, IAC, EGR, etc.

I will say this, I couldn't get it running right and took her to a mechanic and he found the rear of the intake plenum gasket was gone and replaced the gasket, he also installed the distributor (and ICM) for me and checked the timing (and advance), but had to fix several connections in the distributor connector cable. Like I said, it runs great. Smooth.

Cruising along and just all of a sudden the engine isn't running. All the lights, battery, elsewise electronics appear to be running. Cycle the ignition switch off and back on and bam - she's running great again.

1986 F250HD 4x4
5.0L EFI, NP435

ArdWrknTrk

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

Administrator

Mark,
If you have to fix distributor wiring you should look into a remote TFI kit with a heatsink from MCaulley racing or FatFoxx.

What does it say on the radiator shroud sticker, and what is the GVWR of your truck?

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: Engine Stops Running, But Refires if Switch Recycled (off/on)

Administrator

I doubt it is a wiring problem. Turning the key off and back on shouldn't fix wiring, but it seems to cause the engine to run again. Given that, I think you have an electronics problem. Maybe the TFI? The pickup in the distributor?

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

ScubaSteve

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

In reply to this post by MarkThomas

I had a similar problem on my 86 F150 5.0 efi truck when I purchased it. The previous owner fought with the problem and could never figure it out. His mechanic also replaced the distributor and did a tune up. What I found was bad wiring connections in the engine harness for the tachometer signal. The way I understand it to work is the computer primes the fuel pumps when the key is turned on then when the computer get a tachometer signal from the distributor it turns the pumps back on and keeps it on until the engine is shut down and it looses the tachometer signal. I don't think the computer will energize the fuel pump relay again after the signal is lost until the key is cycled again. My truck would randomly die and then start right back up like nothing was wrong. It was a real pain to track down until i got frustrated and pulled the complete engine harness and started checking every wire. The thing that makes it hard to find is that once it stalls you cant tell what happened. Did the pumps shut off because the engine died and lost the tachometer signal or did you loose the tachometer signal and the the pumps shut off.

Hope this helps,

1986 F150, XLT Lariat, 5.8, AOD, 8.8 limited slip, 4.10 gears

Gary Lewis

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

Administrator

You know, that would do it. If you lose the tach signal the computer will shut the engine down. Good idea!

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

Administrator

In reply to this post by ScubaSteve

It's not the tach, it's the leading edge edge of the PIP signal from the distributor, that resets each timer.

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.

MarkThomas

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

In reply to this post by ArdWrknTrk

What you're calling the TFI (Thick Film Ignition), I called the Ignition Control Module - they're the same thing. We installed a new one - Motorcraft - with the new distributor. Do you really think it could be a bad TFI/ICM when both the distributor and TFI/ICM are new?

1986 F250HD 4x4
5.0L EFI, NP435

MarkThomas

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

In reply to this post by ScubaSteve

My truck doesn't have a tachometer - does that mean the EEC-IV doesn't use a tach signal?

1986 F250HD 4x4
5.0L EFI, NP435

MarkThomas

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

In reply to this post by ArdWrknTrk

Isn't the PIP sensor (which is like the old crankshaft position sensor) located in the distributor? Shouldn't that too be new since I bought a new distributor?

1986 F250HD 4x4
5.0L EFI, NP435

MarkThomas

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

In reply to this post by Gary Lewis

Since I don't have a tachometer, how do I know if I lost tach sensor signal? When it happens again, what do I do to see if the pumps are still on? I have a fuel pressure tester, should I keep that in the truck and when it shuts off just coast over on the shoulder and screw the pressure tester on?

1986 F250HD 4x4
5.0L EFI, NP435

Gary Lewis

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

Administrator

It is PIP instead of tach that tells the ECA where the engine is in its revolutions, as shown below. And I don't know what happens if it loses PIP and then regains it. I don't see why the engine wouldn't refire, but I don't know.

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

Administrator

In reply to this post by MarkThomas

There are two different TFI systems, if you install the wrong module you have problems.

The first was Push Start (PS) these trucks will run -with locked timing- if you unplug the SPark Out ("spout") connector.
The Computer Controlled Dwell (CCD) will not.

Then, there's also the possibility the electrolytic caps on the engine management computer are leaking.
Heat affects them also.
But they don't usually come back.

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.

ScubaSteve

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

In reply to this post by MarkThomas

I was calling it the Tachometer signal but as the other guys have clarified its the PIP signal. Either way I was loosing the signal from the distributor and my fuel pumps were shutting off. I found several damaged wires in my harness when I did the repair so I cant say exactly what wire or wire color fixed it. Not sure if this is your problem but its something to look into.

1986 F150, XLT Lariat, 5.8, AOD, 8.8 limited slip, 4.10 gears

MarkThomas

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

In reply to this post by Gary Lewis

I can't get my code reader to work, but last June I was able to download codes the old fashioned way from the procedure in Chiltons using a volt meter and a jump wire. If a PIP were lost, would that show up in the codes?

1986 F250HD 4x4
5.0L EFI, NP435

MarkThomas

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

In reply to this post by ArdWrknTrk

Here's a discussion talking about what you're saying I think:

https://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

They're saying if the PIP or SPOUT are intermittently grounded it results in stall...similar to what I'm experiencing.

1986 F250HD 4x4
5.0L EFI, NP435

MarkThomas

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

In reply to this post by ArdWrknTrk

Just talked to the tech that helped me get it going, he didn't repair any wires near the TFI connector, his were coil wires and such.

So, here's a thought I could buy a new TFI connector:

https://www.wiringproducts.com/electric-module-socket-wire-assembly-1-pc.html

or

https://www.amazon.com/1986-1993-Mustang-Distributor-Module-Harness/dp/B00BXOSY6E/ref=sr_1_3?dchild=1&keywords=TFI+Connector&qid=1611159210&sr=8-3

Replace the TFI connector, that would have all new parts from the distributor out except for most of the PIP/SPOUT wire to/from the EEC IV. I might get lucky and the bad connection is in or near the connector.

1986 F250HD 4x4
5.0L EFI, NP435

ArdWrknTrk

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

Administrator

This post was updated on .

You could replace the plug, but if I were going there I would remote mount it, and solve an ever present problem with these ignitions*, as I said.

If you have an analog multimeter you can ohm out the spout wire from the distributor plug to the firewall, while flexing it around.
You might turn up an intermittent open circuit.

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.

MarkThomas

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

I will likely take you up on that, and checking the wiring to the firewall is also good practice. A near break or short to ground could be in the wiring to the firewall. Since I'll be splicing those wires anyway, might as well check all of it.

1986 F250HD 4x4
5.0L EFI, NP435

Gary Lewis

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

Administrator

Don't miss Jim's recommendation to remote-mount the TFI. Ford had fits with them until they took them off the distributor and put them on the fender where it is cooler.

Gary, AKA "Gary fellow": Profile

1986F150Six

Re: Engine Stops Running, But Refires if Switch Recycled (off/on)

Administrator

Gary Lewis wrote

Don't miss Jim's recommendation to remote-mount the TFI. Ford had fits with them until they took them off the distributor and put them on the fender where it is cooler.

https://www.fourwheeler.com/how-to/electrical/1708-how-to-relocate-the-tfi-module-on-older-ford-efi-v8s/