New coil no spark

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70DUSTER/74SCAMP

70DUSTER/74SCAMP

Sold the scamp ....still got the duster tho
Joined
Jul 30, 2020
Messages
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Location
West Central Indiana
Ok here we go ...... just completed the slant 6 to 318 convert in my 70 duster. All new electrical components are . Distributor, coil, ballast resistor, mopar orange ign box, plugs , cap, rotor. starter solonoid and battery. yesterday i got it running with new coil ran fine, drove down the road to a buddys , had a beer went to leave and no start. pulled coil wire off cap and put it to ground and no spark. so either my new coil took a crap or something else is going on but no spark there or to my wires . everything is new i grounded the ign box very well. all wiring seems fine . its a 4 wire box so 2 go to the distributor one to neg side of coil and one to the ballast resistor. i had it running driving fine no issues and bam wont start any help would be appreciated thank u
 
Do you have any old/ used components "that probably work" that you can swap back in?

Some tests

1...Turn key to run, disconnect distributor pickup and take the engine harness end. Tap the bare terminal of the connector to ground. Each time should generate one nice fat blue "snap" spark
2....With key in "run" measure voltage at coil +. It should be somewhere between 6V and 10V or so. Much lower has a problem, if it is "same as battery" it means coil is not drawing current. That could be a bad box, an UNGROUNDED box, bad coil

3...If you have a tach connected disconnect it. If you have the radio supression cap connected to coil NEG disconnect it. It belongs on POSitive side

4...Connect meter to coil POS and crank engine. Reading should be high, near "same as" battery voltalge. Releasing key should drop reading back down to 6--10V in 2

5..Connectors can be a problem. Worst is likely dist pickup connector as there is no real current there. "Work" the connectors in/out several times to "scrub" the terminals and to feel for tight. Examine with a light for corrosion, oxidation, etc

6...Inspect dist look for strike damage on reluctor, shaft play and wear, rust, etc. MAKE SURE DIST is actually turning when engine is cranked.
 
Last edited:
67Dart273 said:
Do you have any old/ used components "that probably work" that you can swap back in?

Some tests

1...Turn key to run, disconnect distributor pickup and take the engine harness end. Tap the bare terminal of the connector to ground. Each time should generate one nice fat blue "snap" spark
2....With key in "run" measure voltage at coil +. It should be somewhere between 6V and 10V or so. Much lower has a problem, if it is "same as battery" it means coil is not drawing current. That could be a bad box, an UNGROUNDED box, bad coil

3...If you have a tach connected disconnect it. If you have the radio supression cap connected to coil NEG disconnect it. It belongs on POSitive side

4...Connect meter to coil POS and crank engine. Reading should be high, near "same as" battery voltalge. Releasing key should drop reading back down to 6--10V in 2

5..Connectors can be a problem. Worst is likely dist pickup connector as there is no real current there. "Work" the connectors in/out several times to "scrub" the terminals and to feel for tight. Examine with a light for corrosion, oxidation, etc

6...Inspect dist look for strike damage on reluctor, shaft play and wear, rust, etc. MAKE SURE DIST is actually turning when engine is cranked.
Click to expand...

To add to #2 - could be bad ballast resistor? If no voltage at coil, check voltage at resistor to determine if the resistor cooked itself or not.
Unlikely, but worth ruling out.
'New' stuff like ballast resistors seem to be junk in many cases these days.
 
Have a picture of the ECU? New orange are notorious for being junk knockoffs also.
 
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