67 chevelle ignition problem/no spark in "on" position

Sounds like you have a wire crossed/shorted somewhere behind the dash, and the engine stuff shouldn't have anything to do with the lights. If they worked when you jiggled the old switch but now don't...... ground coming loose?


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Ok so here's an update. Still not fixed. I installed a new ignition switch and that did allow the motor to start and run for about 1 minute then the same condition returned, it will turnover/start then not run w/ key in on position. The new switch did not fix the problem where the GEN light and dash light stays on even w/ no key in ignition. I took off the starter wires bc i'd just replaced them and found something interesting. When i ground out the ring on one of the wires the GEN light get's really bright and the tach moves a little (aftermarket autometer). I checked the voltage on that wire and it's getting 6 volts??? I can move the wiring harness those wires come out of and nothing happens with the GEN light, its only when that one wire goes to ground. Is there a particular circuit this wire could short to that has 6v??

check what is powered up on the fuse panel when the ign is off. then start pulling fuses until the dash lights go out. if you pull out the lights fuse and the dash lights go out, then you either have a bad light switch or that circuit is getting power from somewhere else. look around for wires that are melted together,probably from the wires on the headers incident. they may be melted remotely from the headers,not nearby. could be under the dash somewhere. if you pull out a fuse from a different circuit than the lights, and the dash lights go out, then that is probably the circuit that is shorted to the light circuit. you could also try unpligging the light switch and see if the fash lights go out. if they don't then the dash lights are powering up from another source so start looking for a melted harness somewhere. you could also try unscrewing the fuse box and checking the backside for melted connections. have you had the car for a long time so you have a history of what has been going on with it over the years, or is it fairly fresh to you? sometimes you never know who has done what over the years and it could be "rewired" by a realpro before you got it. the other possibility is a new harness from painless wiring or some other supplier. I would try cobalt's suggestion and hotwire the distributor to see if it will stay running with constant battery power for sure. that way you are taking the car wiring harness out of the equation for the actual engine running part of things. if it quits, then at least you know it's not a wiring issue. it could be a module or a pick up coil, an ignition coil, bad engine ground, etc etc. is it an alternator with a seperate voltage reg on the fender, or is it an internal regulator style?
when it quits:
- is there gas in the carb? does it squirt out the accelerator pump jets when you open the throttle?
-does it have a nice blue spark.
dsraven

Hello
I have a 1967 chevelle and I'm having the same exact problems. I installed new HEI, that did not help. I just ordered a new switch.
I wired ther HEI from the battery and it did not stall in the hour that I tested it. Before it would just conk out.

sounds like you have some wires melted somewhere. I think the gen light gets supplied 12v from the fuse panel on one side of the bulb and the other side of the bulb goes to the alt. which supplies a ground circuit so the bulb lights up-until the alt starts to give an output when the engine starts and runs. then the gen bulb recieves an output of 12v (or whatever the alt is putting out) from the alt so both sides of the bulb are then positve and the bulb goes out (no supplied ground circuit from the alternator anymore). that is why at a really low idle sometimes the charge light will be lit but really dim, it is because of the difference in voltage across the gen bulb-that is battery voltage supplied to one side of the bulb, and less than battery voltage to the other side of the bulb. that equals a dimly lit bulb. this is how the dash lights work on some of the newer import cars. battery voltage to one side of the bulb and less than battery voltage to the other side equals a lit bulb, however dimly.
if you disconnect your old power supply wire from the distributor (insulate it so it can't short to ground) then hook up a jumper wire power supply from the battery (with an inline fuse) to the hei positve supply, the engine should start and run as long as you supply the distributor some battery power. that is as long as everything else is ready to run, fuel, air compression etc. if it starts and stays running then put your test light on the old power supply wire that you had hooked up the the hei before. just see what it does, is it lit brightly or dimly or at all? now disconnect the jumper wire and the engine should stop running. now, with the key in the run position, do you have a well lit test light on the old power supply wire? the same kind of "well lit" as if the test light was put on the battery directly? if not you may have a resistor inline. now try the same thing when you turn the ign swith to start. if the test light on the old wire is bright in start but not as bright in run then you probably have the resistor. the old points type cars would have had a ballast resistor inline somewhere or they would use resistor wire in the circuit to the distributor to reduce the voltage when in the run position. otherwise they cooked the coil in no time. they recieved battery voltage in the start position but not in the run position. that is why i had you check the old wire when the engine was running, to see if the test light was dimmer in run that in start. if it is dimmer in the run position then you may need to run a new wire for the hei distributor. make sense?

I need to get a test light for that troubleshooting. I have a new wire going to the coil from the fuse box (no resistor wire) and it did it again. When I had the meter on the coil wire it would jump from 12 volts to 19 volts then 21 volts, just all over the place. It ran best when I directly hooked up coil from battery.

try getting a voltage reading on the fuse panel with the engine off key on and then with it actually running with the jumper wire from the battery. also get a voltage reading at the alternator output during those same conditions and see what you get. they should be the same at the alt as at the fuse panel, otherwise there is a voltage drop somewhere or some short circuits. if the voltage is all over the place there may be an issue with the alt "seeing" the battery voltage, like bad battery connections, a bad battery ground wire or a bad wire from the alt to the battery or a bad terminal connection at the starter. check all the connections at the battery, including where the actual cable wire strands goe in to the terminal-i have seen that cable green inside the insulation even though the terminal looks ok- you gotta take the terminal off the battery and clean the posts and the terminal to be sure don't just look at them visually, and then the ground cable connection on the engine block and frame-nice shiny bare metal, then the terminal on the back of the alt, then connections at the starter, then the ign switch and on down the line. all the positive terminals should have the same voltage, if not there is a resistance somewhere that you have to find. maybe it is a melted wire or a coroded terminal on the back of the fuse box or a bad bulkhead connection through the firewall.....hope it helps, keep us posted

Oh my! it will take me a year to do all this, well at least several days. First I have wrap my brain over these steps. I will install the new ignition switch when it comes in and do some more troubleshooting at that that point. I will post the results. I in the mean time will try to find a diagram for this cars electricial system. I dont know what has been hacked or not. Thanks for the ideas, I will implement them all.

just google "67 chevelle wiring diagram" for a wiring diagram, there are lots of them out there.

Here is a wire diagram I drew up for my 67 camaro..... yours may not have some of the stuff I have but it'll get you in the ball park.

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	Dave 67 Camaro.bmp (385.3 KB, 5 views)
	Dave 67 Camaro 2.bmp (445.2 KB, 2 views)

Here's one for a 66 Chevelle

Attached Files

66 Chevelle wireing.pdf (163.1 KB, 6 views)

Here's a 67 Camaro factory wire diagram set

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