Starting problem making me nuts

[chargercraig]

1968 charger 440
When I go to start the car it turns over but won't start until I release the key to the on position. It has been getting progesively worse.  I've changed everything from the key switch to the starter and everything in between. What ever I change will fix the problem temporarly, but it always begins to reoccur. After a few weeks or months.
Does anyone know a cliff I drive my car off of ( just kidding ) But please help

[BLK 68 R/T]

Lets start with what ignition system you are using?

[chargercraig]

I'm using a mop at electronic ignotion (Orange box)

[BLK 68 R/T]

Ok, so with the mopar electronic ignition you are running a ballast resistor. Have you replaced it, or tried a different one? also pull the engine harness plug of of the bulkhead and look at the terminals on both sides, large brown and blue wires specifically, but they all need to be clean and corrosion free and make sure the wires are not pushing out one side or the other when you plug the harness in. Start with those few things and see what you find.

Wes

[Staxbro]

Check your wiring at the ignition switch end. The reason I am rebuilding my harness is that the blue (run ignition) brown (start ignition) and black (accessory feed) were all clumsily spliced together and getting hot. The yellow wire should go to your starter. If they are hot in the wrong key position or (like mine) physically very bl**dy hot, then investigate your wiring!

[chargercraig]

I still haven't figured this out. It's darndest thing. Initially it'll start right up. When I shut it off and go to start it again, it won't start. That is its not getting spark. It doesn't matter if I ran the car for an hour or for 45 seconds.. And than it won't start again until it sits for a while, like 20 or 30 minutes. And it fires right up again.

[K9COP]

Sure you're not getting vapour lock? Check the wiring for the switch too. With a strong starting, easy running car, they will catch with just the key going to run, but they should have a feed to the coil in start too, I think. This is off the top of my head, so search for my thread on the same issue.

K9

[BLK 68 R/T]

After you get it started is the coil getting hot? It may be going bad internally or there is a wiring issue, that would explain the half hour cool down period before the car will start again. You should be able to put your hand on the coil even after it has been running for a few minutes.

[Bronzedodge]

I still haven't figured this out. It's darndest thing. Initially it'll start right up. When I shut it off and go to start it again, it won't start. That is its not getting spark. It doesn't matter if I ran the car for an hour or for 45 seconds.. And than it won't start again until it sits for a while, like 20 or 30 minutes. And it fires right up again.

That is a bad coil.  It only takes a few seconds of run for it to go open, then it cools and works after 20-30 min.  Mopar did have a bad batch of Orange boxes many years ago - I had one "oscillate" - made an arc from the coil secondary to the primary neg.  Different box fixed it.

[XH29N0G]

I came in late on this and apologize if I missed this.  I have one test to try in addition to the coil checking. Have you checked the key switch with a voltmeter (check voltage from ballast resistor to ground) to see if it is on when the key is in the start position and also when it is in the run position. 

[Pete in NH]

This kind of intermittent electrical problem can drive you crazy and they are often difficult to find until it quits working altogether.

It sounds like a thermal issue, that is a temperature problem. As Wes mentioned above I would check the bulk head connector pins for corrosion and making contact. In the engine cranking position of the ignition key Chrysler systems bypass the ballast resistor. I would also check the orange box ECU connector and pins. The orange box itself might be temperature sensitive anything from a bad component inside to a cracked solder connection on the printed circuit board. You can get "freeze spray" which is basically R-134 in a can that can be used to cool electrical parts down rapidly. Try Radio Shack if you still have one open near you. When the trouble starts spray one part at a time and only one part and see if the car will start. If it does repeat the test a few times and if the car always starts after spraying a certain part you have likely found the problem. I would try cooling down the coil and ECU first.

Good luck and let us know what you find.

[ACUDANUT]

Carry an extra ecu with you and plug it in, then see if it was the box is going bad.  They are only a 20.00 back up. 

[John_Kunkel]

I still haven't figured this out. It's darndest thing.

Will it start consistently when the key is released from Start to Run as in the OP? Did you do as previously suggested and check the condition of the brown wire circuit?

The brown wire (IGN2) is the only source of ignition power when the switch is in the Start position, once the switch is released to Run the blue wire (IGN1) supplies power. If there is intermittent power at the brown wire it won't start consistently.

The firewall bulkhead connector is the source on many firewall-forward electrical problems, check/clean those connector.