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Mallory Unilite Help!!

Bundy

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Jan 10, 2009
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I have the Comp9000 Mallory Breakerless Unilite distributor on my 68' on a carbuerated 90's 302.

I am thinking my dizzy is done, or needs a new module. The votage was very very low at the neg side of the coil with the key on, yet was within Mallory's threshold when the optic module was blocked.

The truck also gets the most spark at the very end of the attempt- for example, when turning over turned to START it get's no spark but as soon as the key goes back to ON it tries to start. with the plug pulled it was very evident that the spark was better when not in START.

Is that the module going bad? is there anything else in the Unilite that can go bad? is it worth trying the module or should i look into a new dizzy

have 3 working coils, tried them all- new starter solenoid and the ignition works. The dizzy is the last thing to be assumed.

Help!

Edit: Testing with Multimeter

With Ignition ON-
Battery + terminal: 12.4V
Coil + terminal: 4.5V-4.6V

Cranking-
Coil + terminal: 10.5V
Coil - terminal: 1.8V
 
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Viperwolf1

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Sounds like the ignition resistor bypass wire is not hooked up. Its small, brown and loves to be attached to the solenoid "I" terminal and positive coil terminal.
 

bmc69

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What Viper said..you really need to hook your meter up to the coil '+' side and watch to see what voltage you have with a) the key in run position b)while cranking it over.

a) should be around 7-9V
b) should be above 11V..even as hihg as 12V depending on condition of yr battery and what its CCA rating is.
 
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Bundy

Bundy

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Its small, brown and loves to be attached to the solenoid "I" terminal and positive coil terminal.

the brown wire coming from the ignition or from the disty? The brown from the disty goes to ground if i remember correctly?


What Viper said..you really need to hook your meter up to the coil '+' side and watch to see what voltage you have with a) the key in run position b)while cranking it over.

a) should be around 7-9V
b) should be above 11V..even as hihg as 12V depending on condition of yr battery and what its CCA rating is.

We did this and it was around 4V when starting, with a brand new red top with 720 CCA
 
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Viperwolf1

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the brown wire coming from the ignition or from the disty? The brown from the disty goes to ground if i remember correctly?

A stock wire is brown between the coil and solenoid. Your dizzy wire is different, but correctly wired.
 

DirtDonk

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Been awhile since I checked one, but 4 volts when starting sounds kinda low to me. Maybe your starter is just pulling too much power away from the system due to it's age? Starter/battery cables loose or otherwise not working properly? Insufficient groundage?
Double check all of your grounds. And if you don't already, make sure you install ground wires from the battery to both a clean spot on the engine block AND the body. Then install a ground wire between the engine and the body. The intake manifold to the firewall is a nice convenient place. A ground strap from one of those to the frame wouldn't hurt either.

I know all of that might be duplication, since it sounds like at some point at least your engine was running fine and now it's not. But it never hurts to double check your main power and ground systems.

And while we're on the subject, why is your solenoid new? Even a new one could be defective, but what caused you to change it? How's your starter acting?
Could also be an ignition switch going bad, but it sounds initially more like what has already been discussed. Check that brown wire from the solenoid that Viperwolf mentioned.

And last, but not least, if you still have a radio noise supressor hooked to the positive side of the coil, disconnect it temporarily to see if anything changes.

Good luck.

Paul
 

Viperwolf1

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We did this and it was around 4V when starting, with a brand new red top with 720 CCA

Measure voltage on the "I" terminal when cranking. It should be nearly the same as your cranking battery voltage. The brown wire carries this over to the coil+ terminal.
 
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Bundy

Bundy

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Measure voltage on the "I" terminal when cranking. It should be nearly the same as your cranking battery voltage. The brown wire carries this over to the coil+ terminal.

The 4 volts was from the neg side of the coil when cranking- the pos read at 12V. The wire between the coil and the solenoid needs to have an "ignition resistor bypass" ? what does that mean? i just have a standard wire running from the coil to the solenoid?

Like i said, as soon as the key goes back to the ON position is the exact moment it gets the most spark and wants to start, but only for the last millisecond of cranking.

the ignition is hooked up correctly and all the grounds are fresh and new. i'm stuck!
 
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Bundy

Bundy

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the coil is generating the spark, the battery is good and the voltage at the solenoid is good, it just isn't being transferred to the dizzy it seems like...
 

DirtDonk

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"Ignition resistor bypass" is the Brown wire that Viperwolf is talking about.
What wiring are you running? Stock original? Or newer aftermarket wiring harness?
Your 12 volts at positive side of coil when cranking sounds better. More reason for it not to be the ignition switch or solenoid at this point. Maybe Viperwolf will have more clues for you.
Since you haven't replaced the coil (original you said?), why not do that before getting a new module. The Ford coils were excellent, but the Duraspark probably demands more from a coil and you'll probably need one eventually anyway. Even though I'm not sure this is the problem yet, a new one wouldn't hurt. I hate throwing parts at something though. It's just the principal of the thing. But...

Paul
 

DirtDonk

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Hmm, in all this testing, did you verify that the module was getting proper voltage during cranking too? It appears that the module is still working if it's trying to spark at any time, but maybe the voltage is dipping too far during crank.
Obviously, the 12 volts at the positive side of the coil is good, but where is the module getting it's power? From the positive side of the coil? Or from somewhere else?

Paul
 

Viperwolf1

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The 4 volts was from the neg side of the coil when cranking- the pos read at 12V. The wire between the coil and the solenoid needs to have an "ignition resistor bypass" ? what does that mean? i just have a standard wire running from the coil to the solenoid?

This is correct. The ignition resistor is between the ign switch and the coil+ terminal. When cranking battery voltage drops low and that causes the voltage through the resistor to drop way low. The factory fix to this is the brown wire. It gives you full battery voltage during cranking only. Don't worry about the coil- terminal voltage.

Like i said, as soon as the key goes back to the ON position is the exact moment it gets the most spark and wants to start, but only for the last millisecond of cranking.

Battery voltage goes back up when the starter is disengaged. This indicates a problem with the ignition system.

the ignition is hooked up correctly and all the grounds are fresh and new. i'm stuck!

The 12v measurement above is suspect. This was measured with the starter cranking, correct?
 
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Bundy

Bundy

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Gentlemen- came home and took some new readings...
Edit: Testing with Multimeter

With Ignition ON-
Battery + terminal: 12.4V
Coil + terminal: 4.5V-4.6V

Cranking-
Coil + terminal: 10.5V
Coil - terminal: 1.8V


This means it isn't the coil, solenoid, or ignition switch then?
 
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Bundy

Bundy

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also, once again when i was getting readings as soon as i let off the key while cranking it tried to start at the very end, once i had moved from START to ON... what on earth does that mean!??
 

DirtDonk

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It simply means that, at 4.5 volts even, your engine is still at least trying it's best to start. But at 1.8 volts, it's not even THINKING about it.

From what you say, it sounds like you have too much voltage drop at the coil. Viperwolf I think has more working knowledge of electricity and coil resistance, but it seems to me that your measurement means that either your old resistor wire now has too much resistance (not uncommon on a 30-something truck), or your coil is bad, giving you that low reading.

Here's an almost sure-thing test for you to try. Simply run a small gauge jumper wire straight from the battery's positive side to the coil's positive terminal and try to start it up. If it fires, then you've probably got a bad wire or connector in the circuit somewhere. If it won't start still, try a new coil.

Just remember, when you do this your key won't turn off the engine. You'll have to yank the new jumper wire off to stop the engine.

Paul
 

68ford

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i helped him yesterday. the wiring is ok, we jumped 12 volts directly from the battery and tried to start it, same readings.

what makes me think its the module, is that mallorys test steps says 1st check for power on pos and neg of the coil. it says if there is battery voltage on the negative side, then block the window and it should drop between 1 and 2(i think they described this as "opening" )
this tells me that at some point in rotation, we should see battery voltage. the voltage stays between 1.5 and 2 volts cranking on the negative side. no change. this tells me that the module is not "doing its thing" to release the built up energy in the coil sending it out the coil wire to the cap.
does that make sense?
another thing we noticed is that when a jumper wire was ran from the pos battery to the positive side of the coil, it arched pretty good. more than what i feel a high end ignition system should draw. not sure on how many amps it was though, i didnt want to blow the fuse in his meter, ill leave that to him ;D
 

DirtDonk

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You should never see full battery voltage to the negative side if you're not getting it at the positive side though. It'll never go higher than the 4.5 in his case, and lower would be expected, since a coil, by it's very design, is chock full of resistance.
So, unless I'm getting the Unilite setup completely wrong, it's not putting voltage into the negative side, just letting it flow through. So to speak.

Can you swap out your coil for his long enough to see if the coil is bad?
And what about the radio noise supressor I asked about before? Is it still intact? If so, remove it before testing anything else. Get it out of the equation.

Even though I'm pointing elsewhere with practically everything I say, I almost always suspect a bad module first and foremost. But this one is just too wierd to ignore the other possibilities.

Paul
 

68ford

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he has tried 3 total coils all very new one brand new, same results.

and yes, 1.5 to 2 volts is on the negative side of the coil and never changes, when cranking with 10.5 going into the coil, still same readings on the negative side with no changes.

always been told the distributor(points or module) is just a switch that releases the built up voltage in the coil. also always been told it does this on the negative side, it would have to since battery voltage is supplied to the other i assume. being i see no fluctuation on the negative side, this tells me the module is not doing anything?
 

DirtDonk

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I see what you're saying about their tests, but I still can't see how it would get 12 volts if it's not present from the vehicle's electrical system.
Is the Unilite getting it's power from a source other than the ignition system's power line (Red w/green)? I assume it's wired straight to the same wire, since they call for reduced voltage (in most documentation anyway) to the module.

Here's what I'd do anyway. Get a new module. Screw it, spend the money. Not because I think it's for sure the culprit, but I thnk it's sensible to have a spare anyway. From what's been described so far, it sounds like the module is working. Albeit at a much reduced voltage from optimum. But still, modules are fickle little devils and plague us from there very existence. So a new one will either fix the problem, or at least tell you what it isn't. And give you a trail spare to boot.

Have you tried disconnecting the coil from the distributor and firing it off manually? Key on (should be 6 to 9 volts at the positive side) and jump the negative to ground. Every time you tap the negative to a ground, you're going to get a super-duper-healthy spark from even a halfway decent coil. Put a full 12 volts to it and you should be able to jump an inch gap with no sweat.

Paul
 

DirtDonk

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Ok, we're thinking at the same time here.
From what I know about the tests, his module is toast. It says right there in black and white if you don't see a change at the negative side of the coil when the optical circuit is opened and closed (cranking the engine or blocking the light), the module needs to be replaced.
Simple.
Surprised you were getting any spark at all though. Damn electronics...

Paul
 
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