No spark until I let off the key - HELP [Archive] - FSB Forums

: No spark until I let off the key - HELP


natesms
08-26-2009, 07:27 PM
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.

:whiteflag

CrazyBRONCOguy
08-26-2009, 07:44 PM
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.

natesms
08-26-2009, 08:30 PM
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.

CrazyBRONCOguy
08-26-2009, 08:44 PM
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.

natesms
08-26-2009, 09:04 PM
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.

CrazyBRONCOguy
08-26-2009, 09:11 PM
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
http://www.fullsizebronco.com/forum/showthread.php?t=146290 is the thread about the kill switch

lostinfords
08-26-2009, 09:13 PM
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

natesms
08-26-2009, 11:30 PM
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.

J&SBroncolvrs
08-27-2009, 11:55 PM
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.

colobronco
08-28-2009, 10:03 AM
The piece under the rotor right?

natesms
08-28-2009, 10:38 AM
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. :banghead

bossind
08-28-2009, 10:38 AM
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.

natesms
08-28-2009, 10:49 AM
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?

colobronco
08-28-2009, 10:55 AM
http://webpages.charter.net/1bad6t/duraspark.html

Wiring diagram.

J&SBroncolvrs
08-28-2009, 01:48 PM
The piece under the rotor right?

That's the one, the little coil with the wires coming off it.

jim cole
08-29-2009, 07:38 PM
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.

78Moose
08-31-2009, 04:12 PM
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?

natesms
08-31-2009, 04:33 PM
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.

natesms
09-01-2009, 12:36 AM
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.

78Moose
09-01-2009, 09:09 PM
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.

natesms
09-01-2009, 10:28 PM
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.

I replaced the plug that connects to the Distributor. In this whole process I actually put a new distributor in...so I was sure it wasn't that. That wire could be your culprit though. Mine tested ok multiple times before I must have moved it to the point where it finally failed. I would cut out that section of wire and put new in. From what I've read these things are very sensitive to voltages, etc.

78Moose
09-03-2009, 08:18 PM
i guess i'm hijacking this thread since natesms problem is temporarily fixed and mine is unresolved. i replaced the pickup coil and nothing still. not only that, the engine "almost turning over" as you let go of the key has gone away now. i used the spark tester that plugs in line with the #1 cylinder and still no spark. i guess i need to start seriously studying my chilton manual on how to narrow down the suspect.

again, the ignition components replaced thus far from first to last: ignition coil, distributor cap & rotor, plugs, wires, duraspark module, and finally the pickup coil. please help me.

natesms
09-04-2009, 04:20 PM
i guess i'm hijacking this thread since natesms problem is temporarily fixed and mine is unresolved. i replaced the pickup coil and nothing still. not only that, the engine "almost turning over" as you let go of the key has gone away now. i used the spark tester that plugs in line with the #1 cylinder and still no spark. i guess i need to start seriously studying my chilton manual on how to narrow down the suspect.

again, the ignition components replaced thus far from first to last: ignition coil, distributor cap & rotor, plugs, wires, duraspark module, and finally the pickup coil. please help me.

Check the wiring harness that comes out of the ignition box, and test all the wires coming from inside the cab into the ignition box. My stuff was testing good until I moved it around some and I found the break inside the plug. I plan on buying a new wiring harness between the ignition module and the dizzy just to be safe.

test coming out of the coil with a screwdriver and the center post on the Distributor Cap. You'll probably have a real weak spark coming off of it when the key is let off. (careful here, I lit myself up a couple of times)

If so, wiring into the distributor would be my bet.

78Moose
09-05-2009, 10:17 AM
i didn't know you could still get the complete harnesses. i would love to replace that whole thing. the wires are so stiff, i'm affraid to pull on them w/out doing some dammage. since your issue is actually inside your plug, you could just clip those ends off and replace the plug with male/female spade wire connectors... if that's my case, that's what i'll be doing... if not just to eliminate the plug being the culprit. thanks for the input.

78Moose
09-07-2009, 01:44 PM
i have to mention a few things. in between the bronco starting and not starting (approximately 4 months)

1. a friend was helping me build a winch bumper (which involved a lot of drilling and welding). note that i designed the bumper to be completely bolt-on, so no steel was welded to the frame. however, there were instances that the bumper had to be mounted to the truck and the two pieces, the winch cradle and seperate bumper/brush guard, had to be connected to the frame to ensure fitment. so, some continuity could have been made between the welder and the bronco... just realizing this. great.

2. i replaced all of the body mounts; which i don't think had hardly any affect on the ignition system so as long as i didn't cut any wiring, which i'm almost positive that didn't happen. but i could have pulled on some imporant wires while liftiing the body off the frame. and...

3. i previously had installed the F-350 brake booster/master cylinder upgrade along with a tsm rear disc brakes with negative results. in the process, following the author's instructions (http://www.ford-trucks.com/article/idx/13/092/article/Complete_Brake_Upgrade_for_1978__1979_Ford_Broncos .html), i gutted the stock proportioning valve in order to improve the line pressure to the new rear disc brakes still with negative results. however, i never added an aftermarket adjustable prop valve because my understanding for adding those was to reduce line pressure to eliminate locking the rear tires (obviously, i could hardly even stop the vehicle with or w/out gutting the stock prop valve). however, a new theory was that the front brakes need more line pressure than the rear. so, my last attempt at making that F-350 brake upgrade successful was to install a wilwood adjustable prop valve inline with the rear brake line. so, i could sit in a comfortable position while working on the brakes, i jacked up the front and rear driver side wheels each time i worked on this project (it took me about 2 1/2 partial days to complete). i guess i set the wheels back down a little too hastily, especially the rear tire because...

my next project was to get the truck running again. when i went to start it (days ago), i got nothing. later, i learned i jarred the gear selector out of the park position while letting the rear tires down too aggressively. i pushed it back into place and now at least the motor turning, but no fire. NOW, after reading a few other posts, maybe i fowled the neutral safety swithch. plus, where the gear selector should line up with the P, the needle is actually pointing between P and R. for neutral, the needle is pointing between R and D. so, i've got a few things to work on here. don't be affraid to call me what you like, i'm still a work in progress.

my next items to check/repair/replace are the ignition switch, gear selector rod, frayed wire at the duraspark module, and fusible links, and lastly, the neutral safety switch. wish me luck, i need it.

78Moose
09-07-2009, 04:53 PM
i also forgot to mention: not too long before i parked it to work on those projects above, i was pulling into a parking spot at work when all of the sudden, grey smoke began bellowing out from the seams of the hood. turned everything off, opened the hood, and the insulation of an entire wire going from the selenoid into the cab was melting off of a wire that was cherry red. after removing most of the wire off with a stick, it severed itself. since then, it has started w/out problems until now. remembering that, i was grazing over the selenoid and opened a can of worms. i found where one side of the burnt wire severed itself... at the positive side of the selenoid.

knowing this, how can the starter still be turning the engine with all of these dammaged wires? all of the fusible links look to be in tact. but a yellow wire coming out of the other side of a rubber connector from the voltage regulator is missing... looks burnt off, but the manuals aren't that easy to read. is there a wire coming from the selenoid to a part of the ignition system that won't allow the coil to provide spark, however enable the switch to tell the starter to turn the motor?

i'm getting overwhelmed here. on a positive note, i did figure why the previous owner tied into the black/green wire coming out of the duraspark module. he tied a skinny wire into it as a kill switch going to a little box under the dash. can't wait to clean out those wires.

78Moose
09-09-2009, 08:30 PM
did ford install a factor alarm? there's a box screwed into the back of the dash on the firewall with a ford label on it. and there's a bunch of wire harnesses that look non ford without any electric tape wrap or wire looms, etc. i'm unraveling a can of worms behind the dashboard. it's so hard to determine what's factory and what's not. i have the three different wiring diagrams, the haynes, chilton, and the Detroit Iron CD. which do yall think is better/easier to read. that skinny wire that ties into my ignition goes to some small plastic box just hanging by its wires. i'm still hunting the rest of the wires that this thing comes from down.

78Moose
09-14-2009, 10:00 PM
ok. still no spark. and at this time, i've replaced the ignition switch. but i got a new inline plug tester, and it still shows no spark. but i was reading the manual that told me to use a voltage tester with the aligator clip on the battery negative and the poker in the positive source side of the coil. there was a bright light. so, it told me, if i get voltage, to test the secondary output of the coil and the BATT, no voltage. so it said, my coil is probably faulty.

however, i installed an only MSD coil in the old one's place, and while trying to start the motor, the coil blew the boot/wire off the coil. so, do i have power to the coil,... while starting?

please help

78Moose
09-17-2009, 08:55 PM
i hooked the spark tester directly to the coil. upon turning the key to start, i get one good spark, and that's it. that's why the coil was blowing the boot off. but, after that one spark, nothing else. i'm still troubleshooting.

some starter selenoids have three prongs; two big ones and one small one. my starter selenoid has four prongs. one large one from the battery, next one small one to start, next small one to ignition, next large one to starter. would my four prong selenoid not be transferring power to the right circuit?

suggestions?

herbigblock
09-17-2009, 09:25 PM
check to see if the ground for the pickup, ya know the one that has two prongs but only one is held down with a lil phillips screw, is hitting anything. i had the same problem with the pickup going out just a few weeks ago, and when i replaced it one the side of the ground thats not screwed down was making contact with the vacuum advance lever. so when my vacuum advance was hooked up it woul just die. so if yours is making contact with anything that might be why its not starting. just a thought. it took me 2 weeks a new pickup and a whole new ditributor to figure it out.

78Moose
09-18-2009, 12:33 PM
ill check that. thank you

herbigblock
09-19-2009, 02:24 AM
no problem just trying to help cuz i know its really frustraing when you run out of ideas

78Moose
09-20-2009, 10:24 PM
nope. the arm from the vaccum advance clears the plate for the pickup coil. plus, i double checked a good ground with the voltage light tester, aligator clip to the positive post of the battery and touched the probe to the ground screw. bulb lit up.

how do you check the actual plug to the duraspark module? i have one great spark upon turning the motor to the start position. so, my problem is somewhere in my starting circuit? i'll keep troubleshooting. thanks anyway.

huggyb1972
09-20-2009, 11:03 PM
Try this you need to know if you are getting the pulse to fire the coil. use a test light or volt meter between + & - on the coil if the light flashes or reading bounces up and down when the engine cranks you've got a problem with the coil, if not the problem is back at the ignition module or pickup inside the distibuter. This is gonna sound silly but does the rotor turn while cranking like a timing chain failure? it happens got ask. Good Luck

78Moose
09-21-2009, 10:02 PM
i'll pull the dist cap & rotor and turn the crank the motor. but it was running before all this. the timing chain was replaced back in '04 with a dual cloyes. do yall think swapping in a davis unified igntion (dui) distributor from performance distributors would bypass all of these issues? it would take away the starting circuit/running circuit issue i'm having. all it needs is a single switched wire. the camshaft does the rest.

huggyb1972
09-22-2009, 01:46 PM
Yes thats fine but the QEM is a good unit your just having problems right now with it. On the other hand Bronco Graveyard has a GM HEI that is a drop in replacement for FORD SBW and BB that only needs one single 12VDC power wire to operate I'm thinking about one for my next toy. Before you do that what changes did you make before it wouldn't start you said it drove to where it is and it's still there.Look at anything you've worked with could be a loose connection or something forgotten. Did you check the power to the coil with your meter like I said before to see if the ignition is pulsing the 12volt to the coil thats what makes it fire thats why it pops when you stop cranking it. Then you look at the ignition module on the fender well and ignitor in the distributor. Have a good one let us know how it goes. ED

huggyb1972
09-22-2009, 01:51 PM
O one more thing make sure there is no metal stuck to the the face of the ignitor this would hold the switch closed and not let the flags do their job

78Moose
09-30-2009, 04:15 PM
she's running again!!! it was the damn pickup coil that i've replaced twice now. oh well, $200 later, i can drive her again. thanks to everyone that helped and to the guy that started this thread.

natesms
10-02-2009, 12:22 PM
she's running again!!! it was the damn pickup coil that i've replaced twice now. oh well, $200 later, i can drive her again. thanks to everyone that helped and to the guy that started this thread.

Glad to hear you got it running again. I had the same problem where I tested something over and over again and it always seemed "good". One of the most frustrating things I've ever had to mess with for sure. hopefully we can help some other people out with this thread and save them the frustration! :banghead