Intermittent Problem

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Tnplumber

Tnplumber

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Here is some background:

1972 Dodge Dart; 33,000 mile survivor; stock electronic ignition.

I am having an intermittent hot start problem. When the car is cold, it starts and runs perfect. You can drive it for an hour without any problems. When you turn the car off, it will start just fine, but if you wait 1/2 hour or so, the car won't start and doesn't have any spark. I have changed the ballist resistor, ignition module, and the coil. The reason I changed them is because they were original to the car. I pulled the wire off the coil while cranking the motor and saw no spark. When I put my bare hand on the fender, I got shocked...hard. With the key in the run position, I have about 7 volts at the positive side of the coil. Thanks in advance.

Scott
 
The pickup in the distributor can also fail under heat. I never thought it could since it's just a winding of wire until one day I had one do it.
 
fishy68 said:
The pickup in the distributor can also fail under heat. I never thought it could since it's just a winding of wire until one day I had one do it.
Click to expand...

I'll try that also

redfastback said:
check all grounds. body to engine to battery to body.
Click to expand...

I replace the negative battery cable also.

Right now the car is working. I just need to learn to jump the coil so I can get it home if I have this problem again.

Scott
 
I got an idea the problem is fuel related. Next time it fails to start hold the pedal to the floor and see if it starts and blows a fuel rich cloud.
Just because there is not a spark that will jump a 1/2 inch and can be seen in daylight doesn't mean there isn't one.
 
Scott if jumping power directly to the coil makes it start the problem is somewhere in the wiring harness not allowing power to the ignition system. Like Red said sometimes you can have spark in the daytime and not be able to see it because it's light outside. I always have to put a piece of cardboard next to where I'm checking spark to shadow it so I can see it in the daytime. Make sure your chasing the right gremlin.
 
fishy68 said:
Scott if jumping power directly to the coil makes it start the problem is somewhere in the wiring harness not allowing power to the ignition system. Like Red said sometimes you can have spark in the daytime and not be able to see it because it's light outside. I always have to put a piece of cardboard next to where I'm checking spark to shadow it so I can see it in the daytime. Make sure your chasing the right gremlin.
Click to expand...

It is definately not a fuel issue. I have pulled the plugs when it is giving me problems they look good. I have tried starting it with my foot to the floor, no good. I believe i have found the problem, seems it is the pickup in the distributor is out of adjustment. I plan on changing that out. I am going to give that a try. Also I think you all are right about not seeing the spark.

thanks,

Scott
 
A fellow mechanic at work told me on old chryslers he often saw intermittent voltage problems to ignition coils due to poor power coming off from the ignition switch out through the firewall connector. The auto-electrical shop he worked at used to power up the ignition circuit(balast resistor circuit) straight off of the battery using a relay whose coil was simply powered up by the ignition switch.This fix is much like the relay fix guys put in for powering up their headlights off of battery power. Hope this may help someone,and hope it makes sense too!!! Not sure if this would apply to a hard starting issue or not....I read in a recent thread that 12volts is applied to the coil during cranking.
 
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