No spark at coil

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danho440

danho440

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OK guys i have a 74 duster with a 440 i have no spark coming from the coil so i replaced the ecu .. still no spark .. so i said what the hell replaced the coil still no spark... i have 12 v at coil until i conected it to the coil then i have 4v .. the question i have does the ballast resistor can it cause you to have no spark .. if so i will replace ..... if not any ideas i am at a loss
 
danho440 said:
OK guys i have a 74 duster with a 440 i have no spark coming from the coil so i replaced the ecu .. still no spark .. so i said what the hell replaced the coil still no spark... i have 12 v at coil until i conected it to the coil then i have 4v .. the question i have does the ballast resistor can it cause you to have no spark .. if so i will replace ..... if not any ideas i am at a loss
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Yes, a blown ballast can bugger up the spark, what kind of distributor are you using. Before replacing the ballast check it with an ohm meter, if you got one, and it should read what ever is stamped on the ballast such as .9 ohms.
If it reads zip its buggered.
 
I think that the ballast resistor is in series with your positive wire to the coil. If it has a high resistance (close to being open but not all of the way) it will show what we in electronics (my trade) call "open circuit voltage". Open circuit voltage in your case would be 12 volts. You can, as a test jump across the ballast resistor. If I am right your car should start. You cant leave it like that because the voltage at the coil will be too high. Good Luck.
 
i have no power away from the coil .. so ther is no power to the dist
 
oh an the resitor is super hot to touch ?
 
coil is new as put in first post .. and then i thought will maybe bought a bad coil put it on my truck no problems .. coil is good
 
Try disconnecting the negative side of the coil and see if the voltage stays up. If it does it's either a bad ignition module OR the negative wire is shorted to ground. Check from the negative wire to ground with an ohm meter.
 
ok THE ECU is New the Coil is New only thing i have not replaced is the ballast..... i have 12 v to the coil but when i connect it to the coil and the ign is on i have arould 5 my ballast is super hot ... before this happened i was running then just quit... so i check spark and i have no spark at the coil so i went and got a new ecu and replaced it ... and got a new coil .. and still no spark.....my question is the ballast will that prevent spark if so i will just replace it they are not expensive
 
Yes if the ballast resistor is burnt out then it wont flow any juice. I think anyways. There what, like $10...why not? You already have tried everything else. You will have an all new ignition system when your done. I had a similar problem. I bought a new ECU, rebuilt the dist., new ballast resistor...the only thing I didnt change was the coil because it had spark. Not alot but it had spark, finally said what the hell bought everything else might as well buy a coil. Sure enough fired right up. I personally hate electrical stuff. It seems like you just chase problems forever lol
 
Just like "superchargeddrt" II also think you have a gound somewhere. From what I've read here, it would have to be after the Ballast. Which is pretty much all the stuff you probably hate to work on. Any of the components after the ballast could be smoked & be providing a ground...but here are some other thoughts.

Are you using a coil that requires an external ballast resistor? They are available with an internal resistor.

The 440 doesn't mean anything when working on this.

Is this a new project or were you driving the cars for weeks then it just quit?

Is your pick-up in the distrib working? You should be able to put an ohms meter across the leads & "see" a pulse as it tries to fire each cylinder.

The ballast can get very warm. When the ballast gets warm, it's telling you that it is working. Not all ballasts have the same resistance. The higher the resistance the more heat it will make.

You shouldn't have 12v at the coil unless the ignition is on...did I read that wrong? Disconnect the neg side of the coil with the ignition on...what do you get? Should be less than 12 & more than 5 depending on the ballast you have installed. Unless your coil has an internal Ballast...then 12.

Is your ECU grounded? It should be. I assume that it is because the ballast is heating up.

This may not be true for you particular model...When in the start position, the voltage comes from the starter rather than the ignition switch. Then when you let go of the key it is applied from the ignition switch "On" position. To troubleshoot this...turn the key on then "jump" the starter at the seloniod.
 
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