Car runs, gets hot, then dies. Cant restart until cooler.

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J

Jon P

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hello all. Brand new to the site. I just picked up a 72 dodge dart with a 440 and 727 auto. Here's a bit of history of the car. Car was sitting for a while and gas was bad. I replaced the gas tank, sending unit, and rebuilt the carb. My issue is the car will start and run to operating temp, then it will die. Then I don't get any spark when I try to restart it. The coil and ECU are very hot (just replaced them) I have searched the other threads on this site and did everything they did. Still no go. I need some assistance.
 
Electronic or points distributor?

If electronic, check the reluctor gap in the distributor .007" with a copper feeler gauge.
 
Pull the center coil wire out of the distributor cap and hold it near/up to a ground and see if it's sparking when you "loose spark"....

Then get an extra spark plug, disconnect any convenient spark plug wire, plug the wire into the spark plug and hold it to a ground and have someone crank it over, and look for spark. Be sure to hold the bottom electrode of the spark plug to a ground.
 
I replaced the fuel filter already. It's an electronic ignition. I thought the gap was .008? Either way, that's the only thing I have not done. I checked the spark from the spark plug wire, grounded it and still no spark after it dies. I changed my coil (Accel 8140) and put in a blaster 2 from MSD and it still gets super hot; as does the ECU. I don't have an orange box, just stock. I started to take off some of the electrical tape going from the coil, distributor and ECU and found a couple of shotty splices. Bottom line, it starts and runs, then gets to operating temp, and starts to shut off. I try to keep it alive by pushing the throttle on carb, but she still dies.
 
download the service manual and start troubleshootin . there are threads already on similar problems good luck .
 
swap out your starter 1nce and watch where the connections are sitting check your fusable link are you using an MSD box it may be sending a false reading make sure it is shielded from any heat source , change out your ballast resistor if you are still running 1 with an MSD . MSD 6al instructions say to bypass the ballast and last , good luck because trouble shooting an electrical problem is the worst problem I ever had in a 40-50 ye4ar old car .make sure you put an extra ground to the motor and the frame .
make sure it is an electrical problem and not a fuel issue. Mopar did have some really bad exhaust manifold designs, for instance the 64 - 66 barracuda"s GL let us know what you find
 
"no spark after it dies"

I gotta say this is a weird one....maybe the charge circuit going through the firewall to ammeter is causing problem somehwere (i say this because i had similar problem recently...but I am running an MSD...but still) I did the bypass thing shown at MAD electrical website....and no issue since.
 
Jon P said:
the car will start and run to operating temp, then it will die. Then I don't get any spark when I try to restart it.
Click to expand...

my guess is there is a wire by the exhaust that is shorting when the car gets heated up... maybe the NSS wiring or one of the wires to the dizzy is close to the exhaust or heads.
 
You could turn your key to run without starting the car and see if your components (ecu, coil) still heat up.
 
Have you tried bypassing the ignition switch. I'v had issues with carbon tracking between the switch contacts.
 
My buddy's A100 did this same thing.

Eventually he/we threw every electrical part at it, to no avail.

As we were pulling my electronic ignition distributor out of his engine I saw the 2-circuit connector (on the harness side) was smashed. I then ran an overlay harness from the distributor 2-circuit connector back to the electronic ignition module's 5-circuit connector and the problem disappeared.

Apparently when the engine was installed the harness got pinched.

Good Luck on your hunt!
 
I appreciate all the help. I will track down the issue. I think that is has something to do with the wiring at the bulkhead. I will look into it.
 
Temp related failure of the ignition modules is common. They'll get so hot they melt the gell coat off the backside before they fail completely. Lift it and turn it over. If the gell coat has a melt or bubble in it, there's a sign.
 
IMO check the wiring for too much resistance. Sounds like the wiring gets hot and breaks down the connection. As others have said, bypass the wiring and see if it helps. One circuit at a time. You really need to get dianostic tools unless you want to just throw parts at it
 
My Duster did this back when it was stock and ended up being the pick up coil in the Dizzy. Replaced it and has worked fine since. Motor not so stock now.
 
I have to ask where has 67dart273 been? I always look for his and redfishes responses to electrical issues, have learned a lot from them. Hope all is well.
 
Do we know what the running charge voltage is?
I'd start with that.
 
jimjimjimmy said:
you will most likely find out its the coil .
Click to expand...

Agreed. But it is getting hot for some reason. I'd make sure everything is grounded really well. Run a ground wire from the engine block to the case of the ignition module. A lot of people think that because it is screwed to the body sheet metal that it's grounded. But in most cases not good enough.

Did you know that MSD says that their coils should always be mounted vertical? Something about heat and shorting out being more likely if the coil is horizontal.
 
Thanks for the input. I will replace the pick up coil and gap it accordingly. I've heard that from a lot of folks now. I appreciate it.
 
When mounting a coil horizontally, make sure the +&- terminals are horizontal as well(9&3 oclock). This will ensure that the oil is covering both terminals.

Also when you say no spark when hot, check power to coil, check ohms at the pickup coil. Is there no spark out of coil or just not to plugs?
 
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