Ballast Resistor vs. Resistor Wire - 67 250

[67 chevelle]

Originally Posted by LockDoc

-
Try hooking a wire from the positive post on the battery to the coil and see if the truck will start. (If it starts you will have to shut it down by unhooking the wire from the battery) If you don't have spark then, the problem is in the coil or distributor.

LockDoc

Great advise

[67farmtruck]

I replaced the ignition switch and I still only get +1.0 V at my ignition unfused port, and nothing when I turn the key.

I tried what LockDoc suggested - ran a wire from the + battery post to the + post on the coil. Confirmed with the voltmeter I was getting +12 at the coil. Turned the key to run and got dash lights (good sign). Turned it to run and the starter kicked for half a second and then nothing. Could not get it to even do that again on subsequent tries.

The coil, condensor, and points are all new. I'm about to pull out the new condensor and put the old one back in for the heck of it.

Any ideas?

[67 chevelle]

Originally Posted by 67farmtruck

I replaced the ignition switch and I still only get +1.0 V at my ignition unfused port, and nothing when I turn the key.

I tried what LockDoc suggested - ran a wire from the + battery post to the + post on the coil. Confirmed with the voltmeter I was getting +12 at the coil. Turned the key to run and got dash lights (good sign). Turned it to run and the starter kicked for half a second and then nothing. Could not get it to even do that again on subsequent tries.

The coil, condensor, and points are all new. I'm about to pull out the new condensor and put the old one back in for the heck of it.

Any ideas?

ingnition switch would be my next guess

[67farmtruck]

I put a new ignition switch in this evening and still had +1 V coming out of the ignition switch in "run" and +1V at my ignition unfused tabs.

And I also swapped out the new condensor and coil for the old ones and the symptoms did not change.

[67farmtruck]

Yes - I have 12V on the red wire at the ignition switch

[ray_mcavoy]

Originally Posted by 67farmtruck

Yes - I have 12V on the red wire at the ignition switch

Are you measuring that with the key on or off?

The reason I ask is because there could be a poor connection (excessive resistance) somewhere in that red wire between the battery and the ignition switch and it will only show up as a voltage drop when under load.

For example, with the key off and no current flowing through the wire, there won't be any voltage drop so you would read 12V on your meter. But when you turn the key to the on (or start) position, the ignition (and starter solenoid) draw current. And if that current is trying to flow through a poor connection it will result in an excessive voltage drop.

So if you were measuring 12V on the red wire with the key off, try measuring it again with the key in the on or start position. If the voltage on the red wire drops way down, follow that red wire back to the battery, checking for bad connections along the way.

[Wrenchbender Ret]

I think you have a bad connector in back of the ign. switch. These are nortorious for burning at the red feed wire connection. A replacement pigtail is available at parts stores.

[LockDoc]

Originally Posted by 67farmtruck

I replaced the ignition switch and I still only get +1.0 V at my ignition unfused port, and nothing when I turn the key.

I tried what LockDoc suggested - ran a wire from the + battery post to the + post on the coil. Confirmed with the voltmeter I was getting +12 at the coil. Turned the key to run and got dash lights (good sign). Turned it to run and the starter kicked for half a second and then nothing. Could not get it to even do that again on subsequent tries.

The coil, condensor, and points are all new. I'm about to pull out the new condensor and put the old one back in for the heck of it.

Any ideas?

Remove both battery cables and clean them good. (both ends). If it is an automatic make sure it is all the way into park (or try it in neutral). Make sure that the ground straps from the back of the engine to the firewall are there and connected. If there are no ground straps there install one from somewhere on the engine to the firewall.

LockDoc

[67farmtruck]

Got it figured out - kudos to all of you guys for helping me learn about my truck's ignition system, and especially LockDoc and ray_mcavoy for helping me think simple when things seemed most complex.

ray_mcavoy made a great observation that I had only checked for +12V at my red ignition wire with the key off. With the key in "run", voltage dropped to +1. Thus, I needed to find the source of voltage drop between battery and ignition.

I recently put a new battery in this truck, so I started with the battery connections. Fusible link looked suspect (couple frayed wires - maybe that's the source of the voltage drop - might have broken when I took the + cable off?). So I replaced that with a piece of straight 12ga wire, but it still wouldn't crank. Then I noticed the negative terminal on the battery was a little loose, so I took off the cable, cleaned both ends and the engine block, hooked it back up real tight and boom - away she went firing on all cylinders!

Lesson learned to always think simple and check your work - great teaching point for my son who wants to drive this truck to prom this weekend.

Thanks to all those who chimed in and helped me learn about this truck's ignition system. Although I replaced a lot of parts I didn't need to, they were cheap and it's money well spent to get my hands dirty on a truck I love. On to the next challenge - brake pedal that goes to the floor!

[LockDoc]

Originally Posted by 67farmtruck

Got it figured out - kudos to all of you guys for helping me learn about my truck's ignition system, and especially LockDoc and ray_mcavoy for helping me think simple when things seemed most complex.

ray_mcavoy made a great observation that I had only checked for +12V at my red ignition wire with the key off. With the key in "run", voltage dropped to +1. Thus, I needed to find the source of voltage drop between battery and ignition.

I recently put a new battery in this truck, so I started with the battery connections. Fusible link looked suspect (couple frayed wires - maybe that's the source of the voltage drop - might have broken when I took the + cable off?). So I replaced that with a piece of straight 12ga wire, but it still wouldn't crank. Then I noticed the negative terminal on the battery was a little loose, so I took off the cable, cleaned both ends and the engine block, hooked it back up real tight and boom - away she went firing on all cylinders!

Lesson learned to always think simple and check your work - great teaching point for my son who wants to drive this truck to prom this weekend.

Thanks to all those who chimed in and helped me learn about this truck's ignition system. Although I replaced a lot of parts I didn't need to, they were cheap and it's money well spent to get my hands dirty on a truck I love. On to the next challenge - brake pedal that goes to the floor!

Good deal!! Glad you got it going. There is always another challenge...

LockDoc

[RichardJ]

The lesson that needed to be learned, is that there is a difference between the starter circuit and the Ignition circuit.

The title of this thread is " Ballast Resistor vs. Resistor Wire ". That alone implies an ignition problem and in your post #3 >>and I'm not getting spark with the key in "start", <<
You can not trouble shoot an ignition problem if the engine is not cranking over.




In your post #14 on Apr 20
>>Now I turn the key and I get I very short burst of power and then nothing.<<

I ask in post #24
POWER??????

If the answer to that was, the engine would not crank over, you could have had it running a week ago.
Efficient trouble shooting requires good information.

[67farmtruck]

I'm sorry to confuse, but that's what I had when I started the thread - an engine that cranked over but would not spark. I realize it morphed into something different, and likely I solved the spark problem while simultaneously creating a problem in the starter circuit.

I considered starting a new thread but wasn't sure if that was preferable to keeping all the information in one place.

Anyway, thanks to all those who weighed in.

[HO455]

After forty years of repairing motorcycles, cars, trucks, tractors, tugboats, and ships, the number one rule of thumb I have is "ALWAYS look at the last thing you messed with". Glad to hear you got it solved.