About a year ago I replaced my control module and that stopped all the at-random stalling I had been having. Guess it's time to do it again. Symptoms: Engine stalls at random, starts right back up. On start-up, does not start while you are holding the key to start, but starts the nano-second you release to ON position. On occasion instead of starting, when you let go of the key the engine instantly stops turning and sounds as if a wrong plug just fired.
Once running, it runs just fine (except for the occasional dying).

Sound consistent with control module problem?

The module I put in is made by KEM.
Any thought on quality of this brand, any recommended brands?
I've heard the names Wells and Blue Grommet; anyone ever heard of them? Comment?

Why are these so prone to failure? Anything I can do to improve/assure dependability of this part?

Keep in mind that this is a plain ol' truck. No racing, no towing, no major hauling. Stock.

Your advice/comments greatly appreciated.

Raul
81 F100 4.9L Six

 

Raul, this is a Duraspark II, right? I guess it could be another faulty module, but this sounds suspicusly like a bad ignition switch. The fact that it apparently has no ignition spark with the starter turning, and then fires when the key is released to "run", leads me to beleive it's the switch.

 

Yes, Duraspark II. I once suspected the switch, so I replaced it -- no change, same symptoms, same day. But since it had the habit of dying once a week or so while driving, I changed the control module. All problems stopped, immediately. Till now a year or so later. That's why I'm thinkin' its the module.

Now I carry the old one in the truck. In case the intermittant failure turns permanent, I can switch back to the old intermittant failing one. In the next week or so I'm gonna buy a new one. All places I have called want more than I paid for the one I have (the KEM) so I'm thinking the KEM is a weak brand, maybe coincidence.

Unless I get advice to contrary, I think I'll go for a new module.

Thanks

 

Raul, since you have already replaced the switch, that narrows it down a bit. I also have a feeling that the trouble is not in the module, either.

Inside the Duraspark distributor, there is a magnetic "pick-up" coil. (Not to be confused with the ignition coil) I think this is what is causing the intermittant spark loss. Before you replace it, check the wiring to it. I think there are two wires going to the coil itself (white and green?), and there is also one (black) wire that is grounded somewhere in the distributor. Make sure the ground wire has a good connection.

You can test the pick-up coil with an ohmmeter. Set the ohmmeter to the high scale. Connect one probe to either wire coming from it, and ground the other probe. Any resistance less than infinity means it is bad. Then connect the ohmmeter between the two wires, (ohmmeter on low scale), and read the resistance. Normal is between 500-1500 ohms. Move the vacuum advance arm when conducting this test, to see if there is a break in continuity.

Since the trouble is so intermittant, the testing may not show up anything wrong. The best test would be when it won't start at all...

Good luck, and let us know....

 

Great advice. I will check it out this week end if I get a chance.

Thanks
Raul

 

OK, this brings us full circle and offers feedback.

I did what thelonerangerxlt recommended, all readings normal.

Replaced my control module. All problems are gone.

Pickup starts right up. Something in the faulty module keeps it from starting while key is in start position (timing??, read on)

The starter no longer has trouble turning the engine as it did on ocassion -- I have read that Duraspark II has a built-in timing retard during start to help the starter a little. The faulty module fails (this is conjecture) to retard the timing and the starter is fighting the pressure in the cyliners)

The engine no longer dies at random.

So my advice -- if your truck dies as if the key was turned off at random, and starts right back up; if it starts right after you return the key to start; or if your starter has trouble turning the engine on occassion (and you know the timeing is set right) -- that may be an indication that your module is about to give up the ghost. I suppose at some point it would fail altogether (but I've never expereinced that).

Thanks for the help. We'll see how long this lasts.

Raul

 

You might want to check and insure that the start circuit is coming up while you are starting the truck. It is the white wire going to the module. It bypasses the ballist resistor and insures that the coil is getting enough voltage to to work it also causes the retard on start to work. Also any time you turn the key off the coil discharges one more time this is the cause of the occasional hit when switch is turned off. We also used to see the start when key returned to run position on point systems and this was caused by a dragging starter sucking all the juice away from the coil. I do believe that the module was bad it happens more often then Ford would like to admit. Also the Wells modules are a very cheap made module and are prone to fail if you look at them the ciruitry is about the size of a credit card instead of the full size board found on the original modules. And who ever makes them for Wells also makes them for a lot of other house brands. Motorcraft is hard to beat in this area I know they are pricey but whats it worth to you to not have to walk home or worse get run over because the truck stalled at the wrong time. Borg and Warner also used to have good units. You mentioned blue tag. Ford identified there duraspark modules by the color of the tab holding down the the wires going into the module. I know they made blue (one of the most common) yellow, red, brown and green and maybe some more

 

Thanks for exellent information. How would one check to see if start circuit is coming up during start? Probe thru insulation of white wire with voltmeter and ground it to see if you have volatge while cranking??

I don't have the problem now -- but I'd hate to pass up an opportunity to learn.

Thanks again.
Raul

 

Raul that is what I would do. Also if the starter solenoid has two small wires on it one will be from the ignition switch the other one will be the start voltage circuit make sure it is hooked up and suppling voltage battery voltage when starter is cranking. When the starter is cranking voltage will drop below 12 volts sometimes as low as 9 volts. Don't like to see it that low but it some times happens.
When the truck is running the coil will only have about 8 volts on it.

 

You've gotten some excellent advise on the ECM, but since mine failed last week, I thought I'd share its symtoms. It was running perfectly, idling at a red light and then it was just like someone turned the key off. After that nothing, starter would turn great, but no spark. Pushed truck off the road, listened to some idiot Chevy truck driver make fun of me, walked 3 miles, bought a new ECM for $34 (Wells at Autozone), 3 hours later it was running perfectly. That was my 3rd, they seem to last 60,000 miles or so.

My 88 model has it mounted on the distributor which I beleive Ford had some kind of recall on, because its in a "high heat" area which makes them fail somewhat prematurely (if you call 4-5 years of use premature.)

 

[updated:LAST EDITED ON 01-Mar-02 AT 09:48 PM (EST)]Stephen yours is the typical failure. It just dies like the switch was turned off. And the TFI will do the samething I have replaced the TFI on my 1984 6 times in 150000 miles keep one in the tool box along with that ******* socket to take the screws out with. Also Stephen I bought a Wells to do sometesting with last week and it only cost me $18.00 at autozoo mine was a blue tab was yours a different color. Also Raul I wanted to mention that I have seen one truck that the wiring harness to the distributor had a seperated wire in it and it would act up on an intermittened bases.