No Spark Question

[N96]

i have been detailing the engine compartment on my 72 340 duster which now has no spark from the coil and wont start. during detailing i replaced the cap, rotor, wires, main engine harness, ecu module, voltage regulator, and coil. i have tried various different parts off my cuda that i had changed for troubleshooting and still no luck. i even put the old harness back on and nothing. any help would be appreciated. mark

[MEK-Dangerfield]

By detailing, did you by chance paint the inner fenders and firewall? I'm thinking the ECU module, or coil bracket might not have a connection to ground anymore(voltage regulator too, but that wouldn't be the problem now). Let's start there... Does the engine turn?


  Mike

[N96]

grounds are good and it cranks no problem

[MEK-Dangerfield]

OK,

  Let's go with the electrical problem. Do you have a volt meter? I would love to know what voltage you read on each side of the coil when the key is turned to the "on" position( the + and - terminals). Might you have messed up the spark plug wires as you replaced them? I'm just trying to narrow this for you. I know all toooo well about this ignition crapola. 


   Mike

[N96]

all the obvious has been tried, ie: firing order, different coil, resistor, ecu, wiring harness, grounds etc. it ran before i took it apart now it wont start. i had the dash apart as in the gauge panel but dont think that has anything to do with it. i do not have a volt meter. maybe something with the distributor, i'm at a loss

[MEK-Dangerfield]

Does your dash have a volt, or amp meter? When you said you had it apart, it struck a nerve. If it is a amp meter, then we might be on to something here.

  Mike

EDIT: All current goes thru the amp gauge if that is what you have. Maybe the lugs were not put on tightly? Where are you located? I know I could solve this in 5 minutes. 


 

[N96]

at first i thought we had it, as i only put the amp gauge wires on hand tight. i went out tightened them up with a wrench and still nothing. the amp gayge does go negative with key on so it is working. next guess, lol

edit: i'm in nj
edit #2: with key on and test light both sides of coil light test light, while cranking batt side of coil is lit, did not check other side while cranking

[Bullitt-]

I have heard of too many people leaving the rotor button out not to ask the question.

[Chryco Psycho]

typically you can buy a Volt meter for around 5-$10  , probably time to invest in one

[duodec]

Use a test light (or analog VOM; digitals are too slow) from coil negative to ground.  When you crank the light should flash on and off.  If it does then you can start on the ignition secondary wiring (coil/cap/rotor/wires/plugs); if not then look at the primary.  If you have power to the coil positive (12V cranking, somewhat less running but I'm not sure what; depends on teh ballast resistor and connections) then you need to doublecheck the ECU, ECU wiring, reluctor, pickup, etc.

How did you test (lack of) spark from the coil?

You didn't mention fuel.  Do you have an electric pump?  If so is there an ignition interlock that might be preventing it from running?

[ShelbyDogg]

Run a jumper wire from the positive post of the battery or starter solenoid to the ballast resistor and crank it with the center coil wire close to ground. Do yo get a spark?    It doesn't matter which side you use on the ballast.

[N96]

with test light on neg side of coil and cranking the light stays lit, it does not flash. i'll try a dist out of my cuda thats the only thing i didn't mess with. thanks so far

[MEK-Dangerfield]

with test light on neg side of coil and cranking the light stays lit, it does not flash. i'll try a dist out of my cuda thats the only thing i didn't mess with. thanks so far

I don't see that being the problem here unless you took the distributor out, and accidently put it back in 180* out of phase. If your test light is lighting on the coil, I think you have enough voltage to have spark. Disconnect a spark plug wire. With an insulated pair of pliers, hold it near the valve covers, or some other ground connection. Have someone turn the enigine over, and see if you get a spark from the wire to ground.


  Mike

[N96]

problem has been solved. a friend suggested running a ground from battery right to module and it fired right up. it was suggested here also that i had a bad ground but nothing was painted so i guess just by changing the module, even double bolting on fender, you still get a crappy ground. thanks for all the replys!!!!

[duodec]

N96,
     glad you found it; it makes perfect sense since the coil is fired by the ECU effectively switching the coil negative terminal connection to ground on and off.  On my '71 (which was originally a points ignition) I had a dedicated ground wire running from the engine ground strap connecting point to one of the ECU mounting bolts.

Rich