ignition problems

[njgalligan]

i have an 84 bronco that is converted with a 302, im using the same ol' duraspark ignition box, but recently the motor started running really rough and the plugs are a dark black soot, checked everything possible, im running just a 2bbl motorcraft carb which is just fine, the onlything i can find is the ignition, i checked voltage to the coil and its only getting 5 volts with the key on and around 3-5 with it running, now if i disc. the 12v wire from the coil and turn the ignition on the volts is 12, now if you disc. the negative side but leave the postive side on there and measure volts its 12 as well as long as your using the battery as the ground for all this, now as soon as you try and test the ground from the wire on the neg side the volts drop again, and the neg side runs into that duraspark box, does anybody know whats going on?? or where i should start

 

[njgalligan]

just an update, i tried anothe coil that i had laying around and same prob, its only when i bring that neg. side into the circuit that the volts drop,

 

[njgalligan]

one other update, this prob. started right after a spark plug wire got riped out from my steering shaft, but the plug was replaced and is getting spark but its not strong, but its not a strong on any of the plugs. when that got ripped out could it have grounded out and caused something to short out?

 

[rangerslim]

might have cracked the distributor cap or rotor button......it might be somewhere around the distributor......module?

 

[njgalligan]

so if you were to test right at the coil, the pos. with the pos. and the neg. with the neg/tach, should you get around 12v?? i did do some testing and if you disc. the neg/tach side and test you do actually get 12v, but as soon as you connect it the volts drop down to 3v, i tried a diff. coil but same effect, could there be an issue to where when you put a load on it the volts drop?? i even took a ground straight to the battery and connect it to the neg/tach side of the coil and tested and it still is only getting 3volts, so would you say its a load prob then and to trace the wires back and look for bad spots or any burnt spots?

 

[njgalligan]

ok last update for today, i tried a diffrent ignition module, and same prob, just getting bout 5volts to the coil, traced wires back to ignition switch and pulled the harness off of it and did an ohm test between the battery terminal on the switch and the run wire that goes to the + side of the dis. and its kinda weird, it starts by jumping up to about 2.2 ohms but then jumps down to 1ohm then goes down to .4ohms and stays there??? im completely out of things to check. anybody else???

 

[wade]

-faulty connections?
-wire broken inside of the insulation?
-worn insulation?
-have you checked for shorts/grounds?

trouble shooting over the computer - sucks.
but I can offer suggestions.

 

[njgalligan]

ive looked through all the wireing i can except under the dash and havent found anything bad yet, i did find something kinda odd out though, i disc. the connector that has just the red and white wire from the ignition module and turned the key on and it didnt mess up the voltage as long as you used the ground from battery to test it other wise if you test both the pos. and the neg/tach at the coil it didnt give you a reading at all. somebody tell me im not crazy, the coil should get around 12volts right??? and the coil only getting 3-5 volts can cause the spark plugs to get that dry soot on them and run really rough?? right?? cuz at this point im kinda running out of ideas. and i havent checked everything for shorts or grounds yet, where would be the best place to check? i know the system gets its grounds from the black wire grounded inside the distributor, and ive checked that all the way back to the ignition module