I have a 1992 Dakota with a 318 that has no spark. I’ve replaced the coil, magnetic pickup and crankshaft position sensor. I’ve tested the leads to the coil with a test light and I’m getting power to both sides when cranking, but I still have no spark. I’m all out of ideas any help would be appreciated.

 

Are you testing for voltage with the coil plugged in? If so, seeing power on both sides while cranking is normal. Now, if you are testing with it UNplugged, and seeing power on both sides, that's not right.

How is the cap/rotor? Are you getting any spark out of the coil at all? (test AT the coil.....)

 

That was testing voltage with the coil plugged in. I don’t have any spark from the coil.

 

Then the PCM is not controlling the coil. It fires it by breaking the ground circuit. That would imply it isn't seeing the engine turning.... but, if that were the case, you should only see power at the coil for a few seconds at initial key on.....

 

I get voltage to the coil for 2-3 seconds after turning the key on, then it comes back when I start cranking.

 

So the PCM IS seeing the engine turning.... which implies the crank sensor is doing its job. If you have a test light, put it across the terminals of the coil connector, (coil disconnected) and crank the engine. Does the light flash?

 

I put the test light across the coil connector and it only flashed when I let off the key, and didn’t light up at any other time. Previously when cranking the coil would get voltage but it isn’t now. I also left out in the original post the problem is somewhat intermittent, some days it will crank and run for 30 seconds or so then die due to losing spark and not start back.

 

Bad crank sensor, or bad ECM...... or the wiring.....

 

I don't know if you figured this out yet, but I might be able to help. It sounds like you have an issue with one of the coil control circuits.

The positive (+) side is the DG/OR (dark green/orange) color wire, which is supplied via the ASD relay. When the key is turned to the "on" position, you should have ~12 volts on this terminal at the coil. If you do not have 12 volts, then you would need to check the ASD relay.

The negative (–) side is the GY (gray) color wire, which is supplied via the PCM. This is the side that is controlled by the PCM, which fires the coil by grounding the circuit thus generating the ignition pulse. If you clip your test light to the 12V battery positive (+) and probe this terminal at the coil, your test light should flash according to the ignition pulse while cranking the engine. If it does not, then you would need to check the coil driver output at the PCM.

(Note: If you find that you do not have ~12V coming from the ASD relay on the DG/OR wire, then you can temporarily run a jumper wire directly from the battery positive (+) to the coil to see if you are getting the proper ignition pulse at least.)