Help! Strange ignition problem continues 1971 440 4 speed

[mbc0724]

Thanks for all of the comments since my last post a week or two ago. But the problem persists. Quick recap: Car starts cold perfectly, runs very well, idles fine, drives without any issues whatsoever. Get to destination and turn off the car; wait 10 minutes; the car will not start again. It just cranks and cranks and cranks. However, wait a few hours, and the car starts right up and drives fine again. No issues. Repeat like clockwork--will not start after driving it around until it is fully cold again.

I have changed the ECU, coil, cap & rotor and ballast resistor. Have searched for bad wires and found nothing. No change in the pattern. I have been assuming this is a spark or electrical issue. But have not ruled out fuel. Yet the car runs and starts from cold so perfectly, and runs so well afterwards, that I cannot see a fuel issue. It seems to be heat-related, since the problem only occurs with a hot motor. But who knows.

Any suggestions to finding the gremlin responsible for this strange problem?

Thanks!

 

[WileE]

Rule out one or the other: When you get to that "no-start" point, see if you have spark at the plug & also see if you have fuel squirting in the carb.

 

[RemCharger]

Check for car b flooding. Next time hold the pedal half down , and give it a long crank to see if it fires

 

[eldubb440]

confirm spark/no spark......... possible vapor lock?

 

[turbine68rt]

What type of base gasket are you using?

 

[pnora]

Have you verified that the choke is open when it wont start? What carb and choke set up?

 

[dasol7172]

Sounds more like your fuel is boiling and its vapor locking until it cools down. try a 1/2 inch spacer and see if that helps keep the carb a tad cooler.

 

[Dennis H]

Heat soak. I gave up and put EFI on.

 

[WileE]

We can all go on and on, it's this or it's that, do this or do that. Pointless. You troubleshoot the symptom. We know it's not mechanical, so it's either electrical or fuel. Eliminate one. See post #2. Then, go from there, and not waste speculation and time on the other.

 

[mbc0724]

Thanks for all the suggestions. Just got off work and tried everything again. Started up perfectly. Drove 10 minutes. No problems. Shut it down and would not restart.

Checked the carb for fuel in the no start phase--plenty of gas down the throat.

Checked the number one plug for spark--no spark.

Checked the coil for spark--no spark.

The coil is new. But I suppose that does not mean it works.

I'm bench testing the old one--seems to be ok but I'm no expert. Just using some you tube video and checking resistance.

 

[Dennis H]

Hold to floor til it spits out black chunks. Big Block hot restart issues are common.

 

[Dennis H]

If 71’s have a Bulkhead Connector, spray an entire can of contact electrical cleaner on it for good measure.

 

[WileE]

Thanks for all the suggestions. Just got off work and tried everything again. Started up perfectly. Drove 10 minutes. No problems. Shut it down and would not restart.

Checked the carb for fuel in the no start phase--plenty of gas down the throat.

Checked the number one plug for spark--no spark.

Checked the coil for spark--no spark.

The coil is new. But I suppose that does not mean it works.

I'm bench testing the old one--seems to be ok but I'm no expert. Just using some you tube video and checking resistance.

That's the way. You got fuel + no spark = electrical. Now, trace the ignition primary circuit to see if the coil gets voltage.

Hold to floor til it spits out black chunks. Big Block hot restart issues are common.

Dennis, it ain't gonna fire up without a spark.

 

[mbc0724]

will do.

 

[Dennis H]

Intermittent. Starts cold. Heat related.

 

[mbc0724]

That's the way. You got fuel + no spark = electrical. Now, trace the ignition primary circuit to see if the coil gets voltage.

Dennis, it ain't gonna fire up without a spark.

Will do. Thanks again.

 

[Mopar Miki]

magnetic pick up in the distributor - a most common failure but overlooked by the rocket scientists on all the forums

connect an ohm meter to the 2 terminals and spin the distributor. The ohm meter will change state from a reading in ohms to open circuit as the reluctor passes the pick up.

 

[WS23U1]

All good advice. Check the spark first but not if you smell fuel! If you smell fuel do as said above and hold the gas pedal about halfway down and crank for a little while and see if she wants to fire up.

 

[mbc0724]

Thanks for all the extra advice. Will keep you posted.