wont start
Senior User
Joined: Mar 2005
Posts: 310
Likes: 1
I'm not real familiar with the DuraSpark system but I know on a Dodge what you are describing is exactly what happens when the ballast resistor dies.
They just have the ballast resistor mounted on the driver side inner fender but I think the DuraSpark uses a resistor wire.
I'm sure if you do a little research you could find out more about it, or somebody who knows more than I will probably chime in soon.
They just have the ballast resistor mounted on the driver side inner fender but I think the DuraSpark uses a resistor wire.
I'm sure if you do a little research you could find out more about it, or somebody who knows more than I will probably chime in soon.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
evam350 is correct. For Duraspark it is a long length of resistance wire bundled in the dash harness.
Easy way to test: turn the key to RUN, but do not start the engine. Measure the voltage at the positive terminal of the coil (BATT) with respect to GROUND and report your results. It should be 6 to 7 volts.
Easy way to test: turn the key to RUN, but do not start the engine. Measure the voltage at the positive terminal of the coil (BATT) with respect to GROUND and report your results. It should be 6 to 7 volts.
Freshman User
Joined: Dec 2006
Posts: 25
Likes: 0
I'd say its a short in the wiring system. I had a similar problem with my truck. I invested in a msd 6 al with a dura spark adapter. Solved my problem. Later I upgraded to a 140 amp ford alt to maintain 12 volts to the msd. Improved a lot of issues. Hope this helps.
Thread Starter
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Freshman User
Joined: Oct 2012
Posts: 33
Likes: 0
It's right around 7.4 7.5 I tryed just a wire from the battery to the positive side of the coil with no change, I'm really lost with this one it seems like everything that could cause it ive replaced
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MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
First off, remove the jumper wire that you added to the coil. There was no reason to do this. The voltage at the coil is supposed to be what you measured (around 7 volts). The wire you added can actually damage the ignition system.
You're saying that the motor starts up while you're cranking, but dies when you let off the key. Is this instantaneous (literally letting off the key is what is killing the engine)?
Disconnect the 2-wire connector from the module, turn the key to RUN and measure the voltage coming from the WHITE wire in the connector (this is easier than trying to guess what went where when you jumped power to the module). Please do not jump any more wires.
You're saying that the motor starts up while you're cranking, but dies when you let off the key. Is this instantaneous (literally letting off the key is what is killing the engine)?
Disconnect the 2-wire connector from the module, turn the key to RUN and measure the voltage coming from the WHITE wire in the connector (this is easier than trying to guess what went where when you jumped power to the module). Please do not jump any more wires.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
12 volts coming from the WHITE wire with the key in RUN. Note that because the connector is often reversed on most replacement modules, the WHITE wire coming from the truck goes to the RED wire on the module. You want the WHITE wire coming from the truck, which is the factory hot-in-RUN circuit.
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Freshman User
Joined: Oct 2012
Posts: 33
Likes: 0
Checked voltage at the connector and was fine, replaced the module again and started right up, it's beyond me how all those parts went bad because of that wire breaking, but thanks everyone for the help
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Yes, I think that is strange too. Anytime a fusible link drops, you must do everything you can to understand why (sometimes they do break apart after 30+ years).
Measure the voltage across the battery terminals while the engine is running to make sure it's not above 14.4 volts. If a truck keeps frying ignition modules, the first thing to check is the voltage regulator. Sometimes they let go and make the alternator charge too hard, which damages the ignition module. In your case, maybe it made the alternator jump, fried the module, then caused some kind of over-current on a load you had running which popped your fusible link. However, if this was a fused circuit, it would have blown a fuse; if it was an unfused circuit you would have smelled burnt wiring. It's a long shot, but the only thing I can think of.
Measure the voltage across the battery terminals while the engine is running to make sure it's not above 14.4 volts. If a truck keeps frying ignition modules, the first thing to check is the voltage regulator. Sometimes they let go and make the alternator charge too hard, which damages the ignition module. In your case, maybe it made the alternator jump, fried the module, then caused some kind of over-current on a load you had running which popped your fusible link. However, if this was a fused circuit, it would have blown a fuse; if it was an unfused circuit you would have smelled burnt wiring. It's a long shot, but the only thing I can think of.