No spark when hot

[torredcuda]

Been having a starting problem when hot-it cranks over but won`t fire.At first I thought it was flooding but turns out there is no spark.Ballast and coil both check out with Ohm meter and I cleaned the dist cap contacts ealier today and it fired right up,drove around and fired up a couple more times no problem.Then tonight I went for a drive and stopped at Walgreens and wouldn`t start again,got a ride home to get the truck and trailer and 10 minutes later when I got back it fired up again.What would cause a no spark when hot-ECU or possibly something else? I run a Mopar orange box that`s been in the car for 15+ years.

[JayBee]

ECU - This happened to my car when I switched over to the Mopar Electronic conversion decades ago. First I didn't suspect the orange box because everything was new. The local dealer did the troubleshooting and discovered it.

[72cudamaan]

That's a common problem with the orange boxes. Other option is the mag. pickup in the distributor.

[anlauto]

Did you test the coil when the car wouldn't start ? Sometimes the coil over heats..

[Chryco Psycho]

the dist pick up coil can do this also & check the gap while you are in there .

[torredcuda]

Did you test the coil when the car wouldn't start ? Sometimes the coil over heats..

Ya, it was still hot and not starting but checked right at .9-1.0 ohm.

[Super Blue 72]

If all the above suggestions look good, one weird place to look at is a bad rotor.  Look for arc marks in the cap and on the rotors.  Years ago Hondas and other makes had issues with this.  Not sure if this is your issue but if everything else looks good... 

[torredcuda]

Could a bad dist cap be causing the ECU to work harder and overheat?I just changed them both out and the cap was pretty beat looking at the contacts.I am going to take it for another drive tomorrow and see if it happens again.I`ll have another ECU and distributer to swap out if it doesn`t start when I get home to see if that cures it.

[500Stroker]

I've had the same problem before.  It was a bad coil when it got hot.  Fine when cold.

[anlauto]

I've had the same problem before.  It was a bad coil when it got hot.  Fine when cold.

  100%

[dodj]

100%

X2

Does that make it 200% ?   

[torredcuda]

It was the mag pickup, I changed the cap and rotor and went for a drive and again a no start after 5 min. in the driveway.I quickly replaced the ECU with a known god unit and still no fire.I then pulled the dist and swapped out the pickup and after a couple drives it`s been startingf ine.Fingers crossed for tomorrow as I`m going on the Moparts New England cruise. 

[Chryco Psycho]

 

[dodj]

Never get tired of being right, eh CP? 

[Chryco Psycho]

Ummm it could have been any of the above , just list all the possibilities , like I say I have made every mistake in the book which is how I learned , I have seen this before , could have just as easily been the coil or ECU . I wired a Cuda , hid the ECU under the battery tray , had to extend the dist wires about 6' , some how & swapped the polarity to the pick up shoul dnto matter right ? Well it intermittently would not start , swap the 2 wires & solved the problem , lots of stupid stuff .