66 ignition

[Jeremy Hedges]

I have a 66 490hp, the problem is it won't stay running. It will start fine, but when the key goes back to the run position it dies. It cranks fine, but there is no fire in the run position. I am going to work on it tonight so any suggestions would be nice. I have changed the ballast, still same problem. Has anyone had this problem and solved it?

Thanks

Jeremy Hedges
#31711

[Louis Kolb]

Re: 66 ignition

I had the same problem with my 1961 Corvette. It was solved by replacing the ballast resistor. Are you sure that your new resistor is good? The resistor is shorted out during starting and supplies reduced voltage to the ignition coil during the run cycle. If the resistor is open, the coil receives no voltage and the engine does not run.

[Stephen L.]

Re: 66 ignition

Place a jumper wire across the ballast resistor. Start the car. If it keeps running then the ballast resistor has a problem. If it dies then you need to troubleshoot the remaining wiring. Actually, you can determine this by checking the voltage to the resistor with the key in the run position. If voltage (12v) is present (single wire connection) opposite end of coil connection (2 wire connection) then your problem is the resistor. No 12v and you have a problem further back in the wiring. If your fuel and temp gauges and backup lights work in the run position, then the switch is OK and you have an open wire between the ignition switch and the ballast resistor. There is no plug between these 2 points. Note: I do not have a 66 wiring diagram.... I am using a 67 wiring diagram and assume these items are the same. Trace the "12 pink" wire from the switch to all items connected to it. Some are "20 pink" to the items above.

[Bryan L.]

Re: 66 ignition

I had the same problem with a friend's 67. It was the ballast resistor as previously suggested. If the b/r was bypassed with a jumper it ran fine. Replaced it and it has been running fine for years now.

BL

[Bill S.]

steve by time time i typed you had it

they way i see it the ballast resister has to be good if it starts at all. it would seem to me to be a ignition switch issue. i would start with jumping the input side (12V) of the ballast resistor to the battery and see if it stays running. that would rule out the feed (ignition switch of wiring to it) basically you start looking for voltage at the coil and keep back tracking until you find where you lose it. one thought is it runs till you go back to run does not add up as this is the crank mode so it Fires then dies when you let off. there are other non electrical issues thet would cause this as well such as carburator.

[Stephen L.]

Re: steve by time time i typed you had it

The ballast resistor is bypassed during the start cycle (key in start position). 12v is supplied to the coil from the starter solenoid during this cycle.
When you release the key to run, the voltage is supplied from the ignition switch via the pink lead, thru the ballast resistor to the coil. This point on the ignition switch also supplies voltage to the meters mentioned, as well as the backup lights. If they do not work in the run position, then the switch or associated wiring (pink circuit) is faulty.

A carb problem would not be directly affected by the START/RUN circuitry/position as described in the original thread.