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Duraspark question

Sporto

Sr. Member
Joined
Oct 10, 2005
Messages
904
I recently got the Bronco back on the road after a major rebuild. This included a new Centech harness.

Since then, I have blown a 22 year reliable Mallory Unilite module, a new Procomp HEI module, and then I installed a complete duraspark setup with a new TFI coil.

I have researched and used the ballast resistor when needed, and have taken it off for the TFI/Duraspark setup per the wiring diagrams that I have been finding.

This setup worked great! The Duraspark module was a cheapo knockoff that I bought out of a yard...

Now yesterday on the way home from work, the engine just died at a light. It was an ignition kill, because the tach needle dropped like a rock and then the engine quit. It started back up and I was able to drive a few hundred yards out of the way of traffic. During this time the engine backfired twice, sounded like a shotgun! It has never...ever done anything like this in the 30 years that I have driven this thing. The engine would start, but run a few seconds and just die. I had a backup module that I plugged in and it got me the rest of the way home about 12 more miles. Did not detect any problems with the engine once I switched out the module.

A few other things...the Ammeter needle bounces like crazy all the time. The guage is almost useless b/c of this. I was wondering if I replaced the regulator would that help and could it have caused my module from acting up?

Is my module shot?

It was not hot to the touch when I checked, nor was it that hot in the engine compartment...

I am at a loss...two distrubutor modules and now this? What could be causing this? I ran this truck for decades without ever having problems like this...

:(

Any input is appreciated.

Rich
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
A new regualtor may help you needle bounce but they usually will still bounce. Make sure all your grounds and other connections are good. One thing I've always noticed is that engine timing seems to affect bounce as well if its got to much timing it seems to bounce more. I dont know if there is some type of feedback from this or not but maybe it has a effect.
Modules go bad I wouldnt be suprised that a 22year old dizzy went bad especailly a unilite they were know to have issues, not sure how good procomp stuff actually is but for the most part I would consider procomp cheap stuff. Cheap duraspark modules also seem to fail easily and since it was used it may have just been time.

A hot duraspark module is a sure sign that its bad plus the fact that it died on you.. I've seen people put a bag of ice on them to help cool them and get them home.
 

Viperwolf1

Contributor
electron whisperer
Joined
Aug 23, 2007
Messages
24,312
Because of the history of ignition failures I would do some measuring with a voltmeter. Stock ammeters can bounce for 2 reasons, the damping spring is worn out/broke or your charging voltage is fluctuating. Digital voltmeters may not react fast enough to see a fluctuating DC current. Analog voltmeters will. If that's the case I think the cause is more likely to be a weak diode in the alternator than a bad regulator.

Another thing I see that I don't like is the use of the TFI coil. Duraspark was never designed to be used with that type of coil and there is potential for module problems with it.
 

dbevans2249

Sr. Member
Joined
Sep 21, 2003
Messages
610
Loc.
Buena Park, Ca.
Triple check all of the grounds. Many if not most of the Centek problems discussed here turn out to be ground related.
The Unilite will be killed quicker than instantly if the ground cable is removed with the key in the on position. So if it was running and something is loose that could have done it. I have run unilite's for more than 25 years and only killed one by making that mistake.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,275
Not only check your grounds, but ADD some if you didn't already. Should have lots of grounding thingies to connect everything together in one big happy loop.

Maybe take the alternator in to an alternator shop instead of the local parts store (unless you've got a good one with experienced techs) to test the alternator. If you get a new one, definitely get a new regulator too. It's cheap insurance, especially if yours is an older unit anyway.

I burned out several El Cheapo Duraspark modules too, when I had 12 volts to the ignition. Didn't know it at the time, but something had happened to the resistor wire and I maintained a full 12 volts to the ignition system. Points would last about 4000 miles and modules about a week.
I ended up buying a Ford Motorsport Duraspark module (made by MSD), sold specifically to run on 12 volts, and never had a problem after that. That was the only thing I changed, and never burned out a module again. Cost me over $100 in the early '80's(!!!!) so was a lot of money at the time.
But it worked.

Paul
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
.

Another thing I see that I don't like is the use of the TFI coil. Duraspark was never designed to be used with that type of coil and there is potential for module problems with it.

I dont believe the duraspark module cares what coil it runs. The module really only tell the coil when to fire it doesnt apply power to it.

DirtDonk I burned out several El Cheapo Duraspark modules too, when I had 12 volts to the ignition. Didn't know it at the time, but something had happened to the resistor wire and I maintained a full 12 volts to the ignition system. Points would last about 4000 miles and modules about a week.
I ended up buying a Ford Motorsport Duraspark module (made by MSD), sold specifically to run on 12 volts, and never had a problem after that. That was the only thing I changed, and never burned out a module again. Cost me over $100 in the early '80's(!!!!) so was a lot of money at the time.
But it worked.

I"m pretty sure that all the modules take a full 12volts its only the coil that has the resistor not the module your failures were probably due to the cheap modules not 12 volt. Not real sure how you were running points and a module maybe that was your issue.
 

DirtDonk

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Messages
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I"m pretty sure that all the modules take a full 12volts its only the coil that has the resistor not the module your failures were probably due to the cheap modules not 12 volt.

I originally thought it was likely the cheapo stuff being crap. After all, it couldn't possibly be any kind of a mistake on my part(!), right? ;D
There were (and are) however, some diagrams that I thought showed early modules getting lower voltage to their circuits too. More a case of me mis-reading the diagrams though, and the memory sticking. On some modules at least, there is a tap into the resistor circuit for the coil, feeding a wire (some are Green w/red, others are Brown) into the module. At the time, that made me think that the modules also required lower voltage.
I'm pretty sure we've had this discusion here in the past, but can't remember if we discussed just what that circuit was for. Since the modules also get a full 12 volt keyed signal, I'm not sure what a lower voltage signal is telling the box. Hmmm, unless it's the "start-only" part that it's sensing? It is the same wire, after the splice to the "I" wire on the starter relay, so maybe that's what it's for? Dunno. You tell me!



Not real sure how you were running points and a module maybe that was your issue.

Doesn't everybody do it that way? Hah, no, the points were burning out every few thousand miles, which is the whole reason I switched to Duraspark in the first place.
First three modules burned out in approx. a week each. Found the MSD-built unit in the Motorsport catalog and moseyed on down to my local dealer for a fix.

Paul
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
Dont know either as I converted mine as well from points so its not orginal. I just used a full 12 volt source as pretty much all the conversion instrutions say. Now if the modules power wire is orginally tapped into the resistor wire then that makes some sense but most if seen show the power wiring tapping in before the resistor. I've never had a issue with mine and its been in for about 13 years or so.. knock on wood.

Gotcha on the points thing.;D
 
OP
OP
Sporto

Sporto

Sr. Member
Joined
Oct 10, 2005
Messages
904
I am not convinced that it is all coincidental with the two dizzies and then the module. I am going to investigate the alternator, and the regulator is older too, it was on the old wiring before the project so it is circa 2003 or so. Alternator is circa 1990...it cannot hurt to change it out if it might be a culprit.

Thanks for all of this info, it is helping me out immensely.

The one take away is to have a spare module on hand at all times!

;D

More to follow!

R
 
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OP
Sporto

Sporto

Sr. Member
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Oct 10, 2005
Messages
904
OK...swapped alternators with one that I know is working, new regulator and new cheapo module.

Drove it a few miles, no more needle hop on ammeter, except a slight discharge bounce when the turn signal is on. All seemed pretty stable...the lights seemed a little dimmer though...not much, but slightly.

I checked the module when I got it back to the garage, and it was cold as the rest of the metal on the truck. No sign of heat whatsoever...

So it seems okay so far...

I did notice what looked like either sand or sawdust coming out of the old module...I was wondering what that could have been...

Thanks again for the assist.

R
 

Viperwolf1

Contributor
electron whisperer
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Aug 23, 2007
Messages
24,312
I dont believe the duraspark module cares what coil it runs. The module really only tell the coil when to fire it doesnt apply power to it.

It may or may not. It does receive current from the green wire. That current is increased with a TFI coil because the TFI coil has about 1/3 the resistance of a standard coil. If that is combined with a deleted ignition resistor then the current is many times what the duraspark module was designed to accept at that wire.
 

ransil

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Sep 6, 2003
Messages
8,122
Make sure the dura spark module case is grounded, run a wire from a dura spark case screw to the ground block.
 
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Sporto

Sporto

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Oct 10, 2005
Messages
904
Make sure the dura spark module case is grounded, run a wire from a dura spark case screw to the ground block.

Randy,
I did that as you had said before. It goes from the case mounting screw to the grounding block.

I think that alternator you gave to me did the trick...

BTW aren't you at the Fawl Crawl this weekend? What are you doing on the computer and CB?

:eek:

R
 
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Sporto

Sporto

Sr. Member
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Oct 10, 2005
Messages
904
Resurrecting an old thread. I have been running the cheapo Duraspark Blue Tab Module with a TFI Coil since this thread about two and half years ago. It is a solid setup. I grounded the case like Ransil said to do, and I do not have any ballast resistors on any of the wires. I very happy with this setup. No ammeter bounce, no problems whatsoever. So this was a very helpful discussion. :cool:

Now I am almost ready to pull the trigger on my EFI upgrade, and I hate to shelf this solid setup.

Rich
 

WheelHorse

Bronco Guru
Joined
Nov 22, 2004
Messages
2,491
Hey Rich, thank you for the follow up post. So many of these never lead to a resolution both short and long term, so it is greatly appreciated.
 
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Sporto

Sporto

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Oct 10, 2005
Messages
904
Hey Rich, thank you for the follow up post. So many of these never lead to a resolution both short and long term, so it is greatly appreciated.

Glad to help! The funny part is, I was researching a Duraspark upgrade for a Jeep CJ that I am working on for a friend, and I found this (my) old discussion thread in Google! LOL! I figured that I should at least provide an update. You're right, too many threads (like this one for example) go unfinished and we're left hanging as to what the outcome was. %)

I think the main takeaway here is that the knock off Duraspark modules are hit or miss in terms of longevity. Try to find a Motorcraft one if you can. Good grounds are critical as far as I can tell.

I have not had any issues with the TFI coil or module not using the ballast resistor on any of the power wires. I grounded everything to a grounding block on the firewall, and I replaced the alternator and regulator and the ammeter problems went away. Whole setup is solid and dependable for two years now. ;D

Rich
 
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