No spark until I let off the key - HELP - Ford Bronco Forum
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post #1 of 39 (permalink) Old 08-26-2009, 07:27 PM Thread Starter
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No spark until I let off the key - HELP

I have no spark at all, UNTIL I let off the key. When I left of the key it runs for a split second then dies.

I actually had this problem when I first dropped the motor in. I changed the wire to which my electric choke was hooked to and it solved it. No idea why though, but has had no problems since. It was running fine when I pulled it in the garage yesterday. Today I have this problem.

I have a brand new coil and ICM. Tried extras of both of those just to eliminate them. Have power to the coil the entire time, even when cranking.

I've jumped everything I know how to and I'm stumped. Anyone have an idea? I searched some on the forum and found one post with the same problem but no solution.



1979 4" Rough Country Lift. 400. 35" Pro Comp Mud Terrains
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post #2 of 39 (permalink) Old 08-26-2009, 07:44 PM
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I had the pickup in my distributer go bad and cuase very similiar issues, changed it out and ran fine.
Might be worth looking into, we swapped in an old one, as on a 460 you can do it without taking off the dizzy.


'92 Eddie Bauer- C6 Swap, 9" Swap, Roller 357W, AFR 165's, Edelbrock Intake, BBK TB, 75mm MAF, SCT Tuned, 4" Lift, 4" Exh, 4.10's, 33's, 18" Weld Wheels, Rear TrueTrac
'78 Custom- 4" Deaver Lift, Mild 460, 8 Point Cage, 4.10's, Rear Spool, 35's, WildHorse Steering&Trac Bar, JBG Soft Top, RedHead Box, Sag Pump, LNL shorties
'02 Harley Edition F-150 '96 F250 '05 Excursion '79 F250 '86 Mustang '95 T-Bird
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post #3 of 39 (permalink) Old 08-26-2009, 08:30 PM Thread Starter
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Quote:
Originally Posted by CrazyBRONCOguy View Post
I had the pickup in my distributer go bad and cuase very similiar issues, changed it out and ran fine.
Might be worth looking into, we swapped in an old one, as on a 460 you can do it without taking off the dizzy.
Just tried that and no difference...also got it off and old distributor though.
The distributor I put it in is new...but I haven't completely ruled that out.

I also swapped out the ignition switch with a known good one, no change.

It almost seems like a ground issue of some type to me, but I really don't know. Like it isn't getting enough juice when it's under load or something.

I tested all the wires coming out of the cab that go to the ICM and the other plug that runs to the motor and everything was hot. The only thing I don't understand is why is there is a red and white wire going into the ICM from the cab. The White is hot with the ignition on, and the red is like a ground. When you key it over though something happens because it is like the red wire loses its ground...this is probably the way it is supposed to be though with those odd color wires.


1979 4" Rough Country Lift. 400. 35" Pro Comp Mud Terrains
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post #4 of 39 (permalink) Old 08-26-2009, 08:44 PM
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The plug with the red and white wires, the white wire is power to the module when in start, the red when in run. I wired a kill switch on mine using the red.

That was how it was explained to me anyways, don't know if that helps you or not.


'92 Eddie Bauer- C6 Swap, 9" Swap, Roller 357W, AFR 165's, Edelbrock Intake, BBK TB, 75mm MAF, SCT Tuned, 4" Lift, 4" Exh, 4.10's, 33's, 18" Weld Wheels, Rear TrueTrac
'78 Custom- 4" Deaver Lift, Mild 460, 8 Point Cage, 4.10's, Rear Spool, 35's, WildHorse Steering&Trac Bar, JBG Soft Top, RedHead Box, Sag Pump, LNL shorties
'02 Harley Edition F-150 '96 F250 '05 Excursion '79 F250 '86 Mustang '95 T-Bird
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post #5 of 39 (permalink) Old 08-26-2009, 09:04 PM Thread Starter
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Quote:
Originally Posted by CrazyBRONCOguy View Post
The plug with the red and white wires, the white wire is power to the module when in start, the red when in run. I wired a kill switch on mine using the red.

That was how it was explained to me anyways, don't know if that helps you or not.
Through the searching I've done it's told me to check "The red wire going to the ICM for power". Well here is the confusing thing, the wires coming out of the cab, the white one is hot when in the run position. When it goes into the ICM the wire colors change in the plug...so the hot white wire coming out of the cab plugs into the red wire going into the ICM...what the heck am I supposed to be checking.


1979 4" Rough Country Lift. 400. 35" Pro Comp Mud Terrains
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post #6 of 39 (permalink) Old 08-26-2009, 09:11 PM
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The same person that told me the above, also said to follow the wires at the connector as sometimes they switched them. So i would go by the ones coming out of the module. In your case the white wire, which sounds like its fine
Duraspark Kill switch is the thread about the kill switch


'92 Eddie Bauer- C6 Swap, 9" Swap, Roller 357W, AFR 165's, Edelbrock Intake, BBK TB, 75mm MAF, SCT Tuned, 4" Lift, 4" Exh, 4.10's, 33's, 18" Weld Wheels, Rear TrueTrac
'78 Custom- 4" Deaver Lift, Mild 460, 8 Point Cage, 4.10's, Rear Spool, 35's, WildHorse Steering&Trac Bar, JBG Soft Top, RedHead Box, Sag Pump, LNL shorties
'02 Harley Edition F-150 '96 F250 '05 Excursion '79 F250 '86 Mustang '95 T-Bird
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post #7 of 39 (permalink) Old 08-26-2009, 09:13 PM
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my old 78 bronco had an issue like that when I installed a new engine, couldn't figure it out, just looking to dress it up until I could figure it out I relplaced the wiring harness going to the coil and it worked, this was 12 yrs ago, found out there was a wire w/ a break in it, who knows it may work for you too...., my 77 crew cab has a bad ign. sw,..... the prior owner replaced the sw. and it would not start, I ran a jumper wire from the + side of batt. to the + side of coil, use key to crank it,... runs... and use key to shut off,.... just the ign sw/key does not provide + to coil, being that I am swapping the cab it made no senese to fix it.

hope this helps..good luck
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post #8 of 39 (permalink) Old 08-26-2009, 11:30 PM Thread Starter
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Thanks for the tip. I'm going to try tracing all the wires. I have power to the coil while ignition swith is on and during cranking, so I'm guessing something to the dizzy.


1979 4" Rough Country Lift. 400. 35" Pro Comp Mud Terrains
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post #9 of 39 (permalink) Old 08-27-2009, 11:55 PM
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Dizzy pick-up. I had that problem, go to PJB there is a thread on it.

The part is only 30 bucks and easy to replace. The coil lets off a spark when you let go of the key which makes it seem like it wants to start, but without the pickup telling the coil to fire, it's a no go. The fact that it tries to start when you let off the key means that the coil is good and the wiring is good.
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post #10 of 39 (permalink) Old 08-28-2009, 10:03 AM
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The piece under the rotor right?

Quote:
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if you still can't figure it out put it back together and take it to a mechanic
"Under my plan electricity prices would necessarily skyrocket" BHO

Truck was stolen & sold for parts Wheat Ridge Colo Black with Red 2 tone. About $20K in the truck. VIN U15HLEC0170
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post #11 of 39 (permalink) Old 08-28-2009, 10:38 AM Thread Starter
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Originally Posted by J&SBroncolvrs View Post
Dizzy pick-up. I had that problem, go to PJB there is a thread on it.

The part is only 30 bucks and easy to replace. The coil lets off a spark when you let go of the key which makes it seem like it wants to start, but without the pickup telling the coil to fire, it's a no go. The fact that it tries to start when you let off the key means that the coil is good and the wiring is good.

I'm going to get a new one early next week. I did change it from another dizzy, but I can't be sure that the other one was good either, that distributer was removed for a reason, it's the only piece that I haven't bought brand new in this process.

Thanks for the tip that the wiring is most likely good, thats a relief, I hate wiring, I was getting pretty frustrated with this one. Decided it was time to take a few days off from the thing when the tools started flying the other day.


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post #12 of 39 (permalink) Old 08-28-2009, 10:38 AM
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There are 2 power wires to the module, one is activated when you try and start/crank the engine, gives a hotter spark to help start the engine - I suspect this is your problem, its not getting power. The other wire is the run wire, or continued power to the module - this one is getting power, this is why you get spark when you release the key.
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post #13 of 39 (permalink) Old 08-28-2009, 10:49 AM Thread Starter
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There are 2 power wires to the module, one is activated when you try and start/crank the engine, gives a hotter spark to help start the engine - I suspect this is your problem, its not getting power. The other wire is the run wire, or continued power to the module - this one is getting power, this is why you get spark when you release the key.

I tested both with a test light, also tested the coil with the test light and it got brighter when I was cranking, so I'm guessing that it is ok. Maybe I should be checking with a voltage meter though?


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post #14 of 39 (permalink) Old 08-28-2009, 10:55 AM
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http://webpages.charter.net/1bad6t/duraspark.html

Wiring diagram.

Quote:
Originally Posted by InfoFord View Post
if you still can't figure it out put it back together and take it to a mechanic
"Under my plan electricity prices would necessarily skyrocket" BHO

Truck was stolen & sold for parts Wheat Ridge Colo Black with Red 2 tone. About $20K in the truck. VIN U15HLEC0170
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post #15 of 39 (permalink) Old 08-28-2009, 01:48 PM
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The piece under the rotor right?
That's the one, the little coil with the wires coming off it.
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post #16 of 39 (permalink) Old 08-29-2009, 07:38 PM
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i had this problem in my 62 galaxie.460cid ford electronic ignition.changed out the brain box(module)reached in the window and bam it was alive.i had a picup cool go but that would shut my truck off going down the road.good luck.
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post #17 of 39 (permalink) Old 08-31-2009, 04:12 PM
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so the coil gets its power source from the duraspark box and/or the distributor, not the ignition switch?... soif the ignition switch has power, that doesn't mean the coil has power? what role does the voltage regulator play with the coil?

FTAC '03
1978 Bronco, 400, 205, C6, 38.5" Hawgs
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post #18 of 39 (permalink) Old 08-31-2009, 04:33 PM Thread Starter
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so the coil gets its power source from the duraspark box and/or the distributor, not the ignition switch?... soif the ignition switch has power, that doesn't mean the coil has power? what role does the voltage regulator play with the coil?
I was also wondering what role, if any the voltage regulator might play in this. I wouldn't think much, but it is the one non-new part under the hood at this point.


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post #19 of 39 (permalink) Old 09-01-2009, 12:36 AM Thread Starter
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Well, I chased it down to a bad plug at the dizzy I think. I'm not real convinced I truely fixed this problem though because one of the first things I did was pull the wiring harness off of a running truck. I put my old harness back on and started retesting the wires and found one to be bad at the plug that goes into the dizzy (had to clip it and test with a meter, it had tested good in the begining.). Put the new plug on and it fired right up. Like I said though I'm skeptical because I did test with another harness first and it wouldn't go. I'm worried I just knocked something else back into working order for the time being, but we'll see.

Thanks for all the input on this.


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post #20 of 39 (permalink) Old 09-01-2009, 09:09 PM
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natesms, that plug you're talking about, it's got to be the one coming out of the distributor... which is connected to the stator inside the distributor. so, the plug you replaced is the one connected to the stator... and then connected where else? just curious, because i have this exact same problem. i just finished replacing the duraspark box, all the plug wires with no result, and sunday, i replaced all of the plugs, distributor cap, and rotor. the only thing left is the stator for me.

i did notice an exposed section of wire on the firewall side of the duraspark box... the idiot before me wired an alarm system that tied in line with the ignition system. it's not touching anything, so it's hard to say that's the problem. i'm going to seal the bare section with liquid electric tape and pray to God after i put the new stator in, then see what happens.

FTAC '03
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