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Old 02-21-2009, 11:50 PM
cudacarl cudacarl is offline
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Default Intermittent Spark

I have a reocurring problem that just when i think i've solved it, it happens again. I have a '73 cuda 4-speed with stock electronic ignition. What happens is the engine cranks but no spark. Only once in a while. When it is happening i can turn the key from run to off and the engine bumps. I've tried different ECU (Orange,Chrome&standard) , ballast resistors. I've grounded everything, (ecu, Voltage regulator, ground strap from head to firewall). I've replaced the ignition switch & cleaned all electrical connections including the bulk head. I replaced the engine harness about 18 years ago but it seems in good shape. What would cause the engine to bump from run to off? Also on the starter relay how does the Ignition wire off of the relay function? Does it supply voltage to the ignition while the starter is engaged and then stop when the key goes from start to run? Could the starter relay possibly be the culprit? thanks
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Old 02-22-2009, 12:13 AM
70AARCuda 70AARCuda is offline
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check where the wiring harness go into the bulkhead on the firewall...that is where my 73 duster is giving me problems...
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Old 02-22-2009, 01:43 AM
wmfd7 wmfd7 is offline
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Have you changed the rotor button, or coil? Sounds like a ground problem with the box, just make sure your battery is good, if you don't have enough volts to the box it wont crank, if it was the starter relay it wouldn't turn over. Don't forget about the fusible link at the bulkhead.
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Old 02-22-2009, 09:49 AM
cudacarl cudacarl is offline
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I had an accel super stock coil that went bad. I found on this site that it isn't a direct replacement as they state. It got to the point the car would crank but no spark all the time. I had to jump it to start it. I took the accel coil off and but the stock mopar coil and and it fired right up with an almost dead battery. I thought that was it because it was fine for about a month. Then it pulled the same BS yesterday morning. Searching on this board i found where someone had the same engine bumps from run to off problem. A guy posted back that he had the same problem and that it was the magnetic pickup in the distributer going bad. The starter relay works fine i was just curious how the I (Ignition) connection on the relay worked. Its cheap enough that i might pick up a magnetic pickup today and change it and see what happens. The thing is it will start fine 50 times then out of know where pull the same thing again.
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Old 02-22-2009, 10:28 AM
peg leg peg leg is offline
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Default Relay

The starter relay gets 12V from the ignition switch start position, and the relay coil is grounded through the neutral/backup light switch on the tranny.
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Old 02-22-2009, 12:16 PM
cudacarl cudacarl is offline
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The cuda is a 4-speed and i have the starter relay grounded. Been that way for 20 years. So you're saying the I on the relay comes from the key switch. I'm still thinking a faulty magnetic pickup.
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Old 02-22-2009, 02:24 PM
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ehostler ehostler is offline
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Correct, the I pole on the relay just means Ignition switch. It should have nothing to do with the noted problem.
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Old 02-23-2009, 04:33 AM
cudabob496 cudabob496 is offline
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http://www.moparaction.com/tech/archive/roadside.html
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