starting when releasing key

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red67gts

red67gts

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my 67 GT "decoy" sometimes will not start until releasing key. It has 78 318 with mopar electronic distributor and stock ecu, msd blaster coil with 4 pin ballast. After around 9,000 mi of driving this has popped up. Most of time it starts right up but occasionally if it winds for 5 seconds and don't start it will then start when releasing key. Replaced ballast but didn't fix it. Ohms check right and brown wire looks ok and connections. Wondering if maybe switch. Any suggestions, thanks Joe
 
yes, it has been running great for about 9,000 mi but just started this
 
test light the two sets of wires that connect to your ballast separately. One should be hot in run, the other is start hot. I'm guessing the Start side, which is closer set to the coil is intermintantly hot. Check the bulkhead connection.
 
when I check everything checks fine. Kinda like going to Dr a quits hurting. It only does it maybe 1 of of 10 times but as soon as it is runnng no problems at all. Hard to diagnose without a complete failure. Usually when a ballast goes it does not cure itself. One reason I was wondering if maybe switch gooing bad,Joe
 
If it's not the ballast resistor check the ground on the control box. I had a '77 pickup that would do that about once every year. I'd pull the control box, scotch brite the firewall and the ear of the control box and it would behave properly for another year.
 
This surely must be in the brown coil bypass circuit. Hook a test light or meter to the coil + terminal, and crank the engine USING THE KEY and NOT by jumpering the start relay

During cranking, the coil + should see "same as battery" voltage and at least 10.5V or higher.
 
thanks, maybe someone will come by that I can get to turn key while I test under hood. Just hard to tell when it is not doing it all the time. Do you think it is possible for switch being problem? I know the brown wire bypasses ballast during start so have looked at it pretty good. Will look at bulkhead where brown wire passes.
 
Don't ya have some clip leads so you can hang your meter/ test light and run the key?

The brown comes direct from the switch through the bulkhead to the coil + side of the ballast, so IF you are not getting this voltage, and the wire is hooked up, it either has to be the bulkhead connector, the connector on the switch, or the switch itself.
 
thanks Del, just wanted to make sure I was thinking in right direction before tearing into switch, thanks Joe
 
To insure a good ground with no voltage drop to chasses (frame of unit) of ignition control devices such as voltage regulator, spark controller, and alternator, run an auxiliary ground loop wire connecting each device and negative battery terminal. Use a # 14 wire, make it up with crimp on eyes, and attach under one of the device’s attaching screws, and case of alternator.


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I incorporated the ignition ground loop in loom wrap. Also I have a ground loop for head and parking lights, and relays.

Sorry about the mess, I changing out the intake gasket on my slant.
 
I had a 69 camaro that would do this and found out that the voltage to the coil would drop while the starter was engaged. Once you let go of the key voltage would pop up and the thing would start. Definitely check the voltage at the coil.
 
cleaned connections in bulkhead, ballast and distributor with CRC electronic contact cleaner and drove it. I started it several times with no problems. Guess it is waiting until it gets an audience to act up again. Didn't see anything that would be a problem but maybe I lucked out, thanks for all the ideas, Joe
 
finally figured it out and all of us were wrong! The air gap between reluctor and pickup was too wide. When using starter it was drawing amperage and would not fire until I let off and it went back to full power. I sure learned something and wanted to let you know as I didn;t think about this being problem since when it started it would run fine. I had even swapped ecu, ballast and switch after cleaning and checking all wires and connections,Joe
 
I usually suggest checking the reluctor gap, but are you SURE you are getting adequate start voltage?

Did you measure it during cranking?
 
yes when a friend came by we checked it everywhere. Didn't actually check reluctor gap but it was way wide. Didn't really know what was supposed to be but had a Haynes manual for 6 cyl and it said .008 so set it there and cranks everytime now. I put timing light on #1 when I am by myself to make sure plugs are getting fire
 
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