Electrical woes
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Elder User
Joined: Jan 2004
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From: Eastern Pa
Electrical woes
So my truck dies and won't restart. Starter spins the engine fine. It's not getting any spark so I figure the control bos is the usual culprit. Put it on and nothing. So I swap out another coil and still no dice. Now I put in a pickup coil and figure theres nothing left. Starts right up. Drive it up the road 1/2 mile and it dies. Now I notice when I release the key from the start positon the truck coughs once like 1 spark hit. Aha. Replace the ignition switch and it starts right up. Today I drive for about 3 miles and it dies. Does the same thing when I turn the key it spins fine but as soon as I release it, it coughs and nothing. Where do I turn from here?
Posting Legend
Joined: Sep 2001
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Also try using a test light instead of the shotgun method.
It is far more cost effective. There is a good ignition system diagnostic in most service manuals but it requires more test equipment. Any good parts store can test the ignition module for free.
It is far more cost effective. There is a good ignition system diagnostic in most service manuals but it requires more test equipment. Any good parts store can test the ignition module for free.
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Elder User
Joined: Jan 2004
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From: Eastern Pa
Well it was't a total shotgun approach. I left out a few things. I did use a test light to make sure I had current to and from the coil. Then after I thought it might be the ignition switch I did check for power at the hot terminals in the switch which I did have. I had to pulll the battery to charge tonight as it is dead, ao I won't be able to do any more checking until I get it back in tomorrow. I purchased a spark checker to see if I'm getting anything at all there. The only thing else I can think of is a possible short somewhere in the primary wire. Other than that I really don't know where to go.
Postmaster
Joined: Aug 2001
Posts: 4,270
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From: Delaware
You are right, it is a short(or leakage) in the primary wire. There is current flowing all the time through the coil. When you turn the switch off, it breaks the circuit and the coil fires. Check your coil, it must be getting hot, or burning out. The leakage could be the module. It is probably not a dead short.
Posting Guru
Joined: Mar 2005
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From: western montana
Get a better ignition system is my suggestion- search the threads and theres a ton of the same duraspark problems. Could be wiring conections or wiring or the box,coil or or or or...yes...you have have to be good at electrical diagnosing which is why I think it is out of many peoples league. I am going to take advantage of the new hei systems for this motor that you can get for $90-115 from a reputable company (ebay). I'll get a couple in case but will know what the culprit is if I have ignition problems as they bypass the managerie of complexity made by duraspark. I forgot the name of the other system that you can put direclty in a pre '77 ford distributor to turn it into an electronic- but that looks good too.
I hear how good this system is but I'm 0/5 on rigs that had it. That doesn't make my cut.
I hear how good this system is but I'm 0/5 on rigs that had it. That doesn't make my cut.
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Elder User
Joined: Jan 2004
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From: Eastern Pa
So Roger what is theis igition called. I've read some posts here on it but it was always pieces people just put together. I think Torque1st was playing with one. I got the battery charged and back in and of course it started right up. I let it run for a while then drove it around the property for a little and it wouldn't die of course. It's waiting till I try it out on the road again. Torque1st mentioned the shotgun method and I just might try that if it dies on the road again. I have extra parts for everything except a resistance wire, but if it doesn't die I'll always wonder what it is and when it will strike next.
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Elder User
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From: not mass
actually odd you mention that if the resistance wire was hacked out or broken... it would burn your iggy up/cut on and off
check the battery wires and cover the basics
find a continuity checker?? electricity leak tester and run every wire
clean, check and dieletric grease every connection
put 1/4 inch spacers under your duraspark box
sacrifice a chicken on the air cleaner and swing a dead cat by the tail over your head
and let us know
check the battery wires and cover the basics
find a continuity checker?? electricity leak tester and run every wire
clean, check and dieletric grease every connection
put 1/4 inch spacers under your duraspark box
sacrifice a chicken on the air cleaner and swing a dead cat by the tail over your head
and let us know
Last edited by battered_bronco; Dec 10, 2005 at 06:24 PM.
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Posting Legend
Joined: Sep 2001
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The "one wire" HEI systems reduce complexity but you loose the timing retard function on start feature that reduces the load on the starter increasing its life. -Tradeoffs At least with the HEI systems you can get replacement GM parts for them off the shelf at any parts store.
At least with the HEI systems you can get replacement GM parts for them off the shelf at any parts store.
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Elder User
Joined: Jan 2004
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From: Eastern Pa
I've done some other testing and here is what I've found. It won't start now. There is power to the + side of the coil. If I put a test light on the dist side of the coil while cranking there is nothing coming out there. If unplug the dist plug and check for power at the dist side of the coil there is none. I swapped out a coil and it did the same thing. I continue to get the brief fire as I turn the key off. Danlee said that is the coil firing as the circuit is breaking and I guess that makes sense. I can read a wiring diagram just enough to get in trouble. Are there any of the wires either from the control box or anywhere else that I could check for continuity that would tell me where the problem lies? Is the greeen/yellow wire on the dist side of the coil a key to this? Any more suggestions would be appreciated.
Postmaster
Joined: Aug 2001
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From: Delaware
A current through the coil primary charges it up. When the circuit breaks, the coil discharges through the secondary circuit, which produces a high voltage and a spark across the plug gap.
The primary current is from the battery (+12V), throught the limiting resistor (wire?), then to the coil (+) terminal, through the coil winding, then from the coil (-) terminal to the dist. The dist supplies a ground which completes the primary circuit. Normally the dist. breaks the circuit at the right time and causes the spark. If your ignition switch is causing the spark, it is because the switch is breaking the circuit.
If the coil is charging, there must be current flowing. If you disconnect all connections to the coil (-) terminal, you should read the open circuit voltage (about +12V) on that terminal. If there is no voltage present at that location, then the coil must have a short to ground. Do you have a metal case or sleeve on the coil?
If you get a voltage on the coil (-) terminal after diconnecting all leads, replace them one at a time and recheck the voltage. There should be only one lead. It goes to the dist.
The coil case should be grounded to the chassis through it's clamp. That ground is the return for the secondary circuit.
The primary current is from the battery (+12V), throught the limiting resistor (wire?), then to the coil (+) terminal, through the coil winding, then from the coil (-) terminal to the dist. The dist supplies a ground which completes the primary circuit. Normally the dist. breaks the circuit at the right time and causes the spark. If your ignition switch is causing the spark, it is because the switch is breaking the circuit.
If the coil is charging, there must be current flowing. If you disconnect all connections to the coil (-) terminal, you should read the open circuit voltage (about +12V) on that terminal. If there is no voltage present at that location, then the coil must have a short to ground. Do you have a metal case or sleeve on the coil?
If you get a voltage on the coil (-) terminal after diconnecting all leads, replace them one at a time and recheck the voltage. There should be only one lead. It goes to the dist.
The coil case should be grounded to the chassis through it's clamp. That ground is the return for the secondary circuit.
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Elder User
Joined: Jan 2004
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From: Eastern Pa
Ok, I disconnected all the leads and when cranking I have a little more that 9 volts on the - side of the coil. The red lead going to the control box does have power to it. I have 3 leads in the plug from the distributor. Still no spark at the plug. I'm getting lost here.