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Old 02-19-2012, 06:18 AM   #1
coach
 
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Default electrical or fuel puzzle 428 super cobra jet

Selling a 69 mach 1 428 super cobra jet. Drove the car this summer (drove fine)(9 yr old restoration) put it in storage (with stabile in gas) in Oct, took it out(yesterday, Feb 17) and drove and within in 6 miles it was skipping, stalling, wouldn't idle and when I went to turn key off the car kept running. History of car, I am selling it for a friend that has passed away and had the buyer here. Felt bad for him, but the car has always performed well, this was totally unexpected.
I am not a mechanic. Any help would be appreciated.
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Old 02-19-2012, 08:44 AM   #2
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Too easy. The 428 was equipped with a Holley carburetor. Five months of drying out have trashed the carb, so the metering body gaskets have shrunk and are cross-flowing between circuits. A quick rebuild of the carb should do the trick. No adjusting will be needed, just get the new gaskets in and it'll perk right up.
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Last edited by 2+2GT; 02-19-2012 at 08:46 AM.
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Old 02-19-2012, 10:47 AM   #3
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Thanks, I didn't restore the car, pulled the air cleaner and the carb is an edelbrock,
also why would the car keep running after I turned the key off. The car has been stored every winter since restoration and never an issue (always put stabile in the tank also).
It has an automatic choke which also works fine. I don't know if there is petronix ignition or he used points, Again, any suggestions greatly appreciated.
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Old 02-19-2012, 12:26 PM   #4
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Default electrical/gas problem 428 cobra jet

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Originally Posted by 2+2GT View Post
Too easy. The 428 was equipped with a Holley carburetor. Five months of drying out have trashed the carb, so the metering body gaskets have shrunk and are cross-flowing between circuits. A quick rebuild of the carb should do the trick. No adjusting will be needed, just get the new gaskets in and it'll perk right up.
thanks for responding, I sent a reply but don't know if you got it., I did not restore the car, so pulled the air cleaner on the motor and it is an edlebrock carb, as I said the car has been stored every winter, he always put gas stablizer in the tank, as did I, and it has run like a champ. Then yesterday as I was showing it to a buyer (of all times for something to go wrong) it started stalling as you downshifted, wouldn't idle, (the automatic choke works fine when you first start it) and then when I turned it off (the key) the engine kept idling.
Don't know if the car has points or petronix ignition any other suggestions would be greatly appreciated.
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Old 02-19-2012, 02:17 PM   #5
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Hmmm… Is there any power to the coil when you turn the ignition off, and it's still running?
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Old 02-19-2012, 03:11 PM   #6
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Default electrical/gas problem 428 cobra jet

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Hmmm… Is there any power to the coil when you turn the ignition off, and it's still running?
Will look at it in the AM, working today. The coil did feel very warm.
thanks for getting back to me
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Old 02-19-2012, 09:25 PM   #7
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I know you said you put stabilizer in it but I would try some fresh gas...Last year my 68 would not fire up after sitting over the winter...After trying everything I could think of I finally gave it a splash of fresh gas and it fired right up...With the old gas it would not spit or sputter or even back fire..It was like the gas had turned to water.
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Old 02-19-2012, 09:29 PM   #8
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Quote:
Originally Posted by 2+2GT View Post
Hmmm… Is there any power to the coil when you turn the ignition off, and it's still running?
I am wondering if it's actually just running on(dieseling) because of poor fuel after sitting...Did the engine actually idle smoothly with the key off or was it knocking and thrashing around in the engine bay?
Bad ignition points would make it run poorly but it wouldn't explain why it would keep on running with the key off.
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Old 02-20-2012, 07:07 PM   #9
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Default electric/fuel 428 cobra jet

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I am wondering if it's actually just running on(dieseling) because of poor fuel after sitting...Did the engine actually idle smoothly with the key off or was it knocking and thrashing around in the engine bay?
Bad ignition points would make it run poorly but it wouldn't explain why it would keep on running with the key off.

Good point, I put some better gas in and some dry gas incase there was moisture but did not improve it. The idle after the key was off was fairly smooth, don't think it was dieseling.
Am going to check the distributor and coil and solenoid, Again, thanks for your imput
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Old 02-20-2012, 07:17 PM   #10
67 evil eleanor
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When you turn off the key and it keeps running, how do you stop it? Also having a EB carb gives a hint that the engine may have a lot of compression, this could explain the diesel effect. I would suggest some high octane fuel if this continues, the tank will need draining.
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Last edited by 67 evil eleanor; 02-20-2012 at 07:20 PM. Reason: more info
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Old 02-20-2012, 07:17 PM
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2010, 428, cobra, cobrajet, idle, ignition, jet, solenoid, stop, super

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