1970 w/454 starts then dies once the key is let go - Impala Tech
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post #1 of 5 (permalink) Old 03-02-2012, 05:25 PM Thread Starter
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1970 w/454 starts then dies once the key is let go

I just got back from Korea and the car got neglected for about a year... for the most part it ha been running just fine. Today i took the carb off cleaned and oiled it up then took it for a spin. I noticed that it was hesitating if i punched it a little (not floored) and would backfire out the carb (only in low RPMs).

So i went home did some research and decided to look for a vacuum leak since that could be the problem and i could hear a distinct whistling sound while it idled. I went to the car 15 mins after driving around and now it wont stay running.

It will turn over just fine and start, but as soon as i let go of the key it dies instantly. If i turn the key and gas it a little the RPMs will shoot up as long as i have the key turned but once i let go of the key it dies not matter what.

I checked the carb gets gas when the throttle is pushed and the battery is 1 day old. the carb is about 2 years old Holly 770 CFM and its been running great other than the hesitation at low RPMs.
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post #2 of 5 (permalink) Old 03-02-2012, 05:33 PM
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Some how you have lost the ignition power to the coil that fires the car. You are running off the back feed circuit that was built into all points equipped cars that feeds full battery voltage (which often falls as low as ten volts when cranking) to the points that are normally fed by a resistance wire that drops the volts down twenty five percent from what ever the alternator is out putting to preserve the points from pitting.

This is not uncommon as the resistor wire is brittle and subject to corrosion over time. I would check with a multi meter to find out where in the circuit your power is being interrupted (It could be the ignition switch which has moving parts that wear with time).

Big Dave
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post #3 of 5 (permalink) Old 03-02-2012, 05:49 PM Thread Starter
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Any recommendations on where to look without a multi meter and what to look for? i just moved and the movers broke mine (got some weird oil all over it). Just some quick places i could look... i'm not in a hurry so i'm gona wait to get a multi meter.
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post #4 of 5 (permalink) Old 03-03-2012, 11:45 AM
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Wiggle the firewall connector, or better yet, take it apart and clean the terminals. Make sure you disconnect the battery before you do this.

Tom

1965 Impala SS Tahitian Turquoise 427 4 Speed
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post #5 of 5 (permalink) Old 03-03-2012, 12:08 PM Thread Starter
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ya i got it working took a few things off and retightened everything and it started right up.
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