Won't spark until i let off the key??

OonDeanisS · Jun 27, 2005

my car cranks fine, but the spark from the coil to the distributor doesnt fire until i let off the key. Whats backwards here? thanks

rowdie- stang · Jun 27, 2005

Do you have a different "engine harness" from the factory one?

90mustangGT · Jun 27, 2005

Ignition switch???

OonDeanisS · Jun 27, 2005

i duno what an engine harness is, but it's only been doing this since i took out the dashboard, but i dont see any loose wires.

HISSIN50 · Jun 27, 2005

By let off the key, do you mean move from crank to run? It sounds like something in the ignition switch got moved around or is jumping.

Good luck.

rd · Jun 27, 2005

This sounds like a classic case of getting power to the coil in the run position but not the start position on the key. If it happened after the dash work, you may have bumped the ignition so that it does not make contact to power the coil in start.

It could be that the start power wire has a problem somewhere, like at the connectors.

OonDeanisS · Jun 27, 2005

i didnt know the coil had different positions... hmm... that makes sense though. ok so where is the start power wire?

OonDeanisS · Jun 27, 2005

yes hissin, but i dont even know where the ignition switch is.

HISSIN50 · Jun 28, 2005

OonDeanisS said:
yes hissin, but i dont even know where the ignition switch is.

I think RD and I are dancing around the same idea here. It sounds like a nice place to start (I am not familiar with 4 eye wiring enough to offer schematic assistance).

Good luck.

Ranchero5.0 · Jun 28, 2005

Sounds more like a duraspark dissaster.

Oon, for a quick check you'll need to unplug the little red wire on the starter solenoid and check for voltage at the coil positive terminal with the key to 'run' and 'start'. If it's good then check the duraspark box for voltage to the red harness wire in 'run' and the white harness wire in 'start' Since you have an EFI car converted to carb you may be in for a bad time. Good luck.

Jamie

OonDeanisS · Jun 28, 2005

it was a 4cyl. And I dont think any part of my car is Duraspark. My coil and ignition box are both MSD.

jrichker · Jun 28, 2005

OonDeanisS said:
it was a 4cyl. And I dont think any part of my car is Duraspark. My coil and ignition box are both MSD.

You probably have a Duraspark type distributor since the car runs a carb and not EFI. The trigger mechanisim is different between the EFI & Duraspark distributors.

crazypete · Jun 28, 2005

Happened to me too. My Crane hi-6 lost power during cranking and would come on when put to run. My diagnosis: the starter was sucking all the juice out of the system. I wired the ignition to battery power with a manual trigger switch also tied through battery power and problem solved. Odd thing is, I can take the key out and the car continues running if I dont turn the ignition switch off.

Blk91stang · Jun 28, 2005

Wow! I delt with this problem for over 3 YEARS!!! Well here's my story and I'll get right to the points..

Car would unexpectidly shut off while I drove around. Trying to restart the car proved nothing until we waited about 20 min to let it cool down, it would than fire back up. Car was fine for a year than started doing the same crap. Put a spark checker on it to find it sparking only when I first started cranking and than let go of the key.

I will list the parts I replaced and fixed that seemed to help some but yet the car still shut off driving on the street but the car fired right back up again (I think it was luck).

BTW: My car had all of these items on it already, just replaced them with new ones. All except bypassing the factory harness with a seperate ignition switch.

Items replaced from first to last:

1) Wires and plugs
2) All Grounds
3) MSD Blaster 3 Coil
4) Solenoid
5) MSD Billet distributer
6) New Battery
7) Ignition Switch
8) Took apart and cleaned all connections
9) Bypassed factory ignition harness and have a seperate switch to turn on MSD Box.

All of these things seemed to help but the problem still arose when it felt like. As a final attempt, the car just received a new MSD 6AL box along with a new MSD Timing Controller. Have not driven it yet since these were replaced.

There's nothing left to replace as far as ignition goes on my car so if it does it again, I'm gonna light the car on fire. I'll let you know if these 2 things fix the problem or not cause I'm out of ideas if it doesn't..

OonDeanisS · Jun 28, 2005

crazypete said:
I wired the ignition to battery power with a manual trigger switch also tied through battery power and problem solved.

so how did you do this?

Click to expand...

txstang84 · Jun 29, 2005

a similar fate has befallen me...only it was my own doing from relocating/modifying my underhood harnesses...

but since you said it didn't do that until you pulled the dash, then i'm more inclined to believe that's where your problem lies...are you sure you didn't disconnect any wires when it was off by accident? oh, and btw your ignition switch is on the underside of your steering column neatly concealed under the same trim panel as your fuse block...you can distinguish it from all the heavy gage yellow and red wires that terminate into the switch.

oh...and making a "bypass" ignition circuit works, I've seen friends do it in the past...but it's not always the best idea...it remedies the immediate problem, but you may have some deeper issues with your dash wiring which may lead to bigger problems down the road.

my advice: get a complete ignition/starting/charging circuit wiring diagram specific to your 'stang, and start shooting wires...like I mentioned before, I've got the same problem right now, if I find anything I'll let you know though

txstang84 · Jun 29, 2005

crazypete said:
Happened to me too. My Crane hi-6 lost power during cranking and would come on when put to run. My diagnosis: the starter was sucking all the juice out of the system. I wired the ignition to battery power with a manual trigger switch also tied through battery power and problem solved. Odd thing is, I can take the key out and the car continues running if I dont turn the ignition switch off.

like i just mentioned in the reply i just posted, it works, but not always the best idea...oh, and the reason your car still runs when you pull the key out...as long as 12v still is being fed to your hi-6 through your rigged 'igntion' switch, it will continue to fire off the coil when it gets the signal from the dizzy...thus keeping your car running-the only downfall to this? since your alternator no longer has a 12v signal to the field (since you turned the key off-that's also happened in my experience from the same setup), it will no longer charge the battery and you will slowly kill your battery

crazypete · Jun 29, 2005

Oh I know, I wired the car myself. My hypothesis is that the alternator feed is not in an optimal bundle anymore with the mains ooooor the grounding at the front sucks (more likely since sometimes the car just goes cold dead while cranking with a pop sometimes and I need to unplug and reconnect the battery cable to bring it back).

The factory "ignition module" is the EEC so I dont even know....you would run the eec energize lead directly to the battery and splice a switch inline.

This would be extremely ghetto. Dude, you need to probe the +/energize leads on your eec with an analog voltmeter while cranking and see which one is going dead.

OonDeanisS · Jun 30, 2005

thanks ill look for that...

Correct me if i'm wrong, but i should bypass the ignition switch which is next to the fusebox and replace it with a manual switch between the yellow and red thick guage wiring?

crazypete · Jul 1, 2005

The ignition switch is under the column.

My humble opinion in this matter after dealing with a failing electrical system myself is that you can loose a lot of equiptment (eec, maf and tps) from a faulty or badly grounded electrical system. For me, it was a ground that was slightly hot (2-3 volts). If you bypass the switching and run the car with a short then you might end up having to replace lots of expensive material.

So before you do this, open the passenger side kickpanel and pull out the eec. Trace the bundles up and one bundle will be the input and output wires and the other will pass through some relays. That relay bundle is the power block. Your ignition system is basically regulated from the eec. So if it's going off while cranking, either your eec, your tfi module on the side of the distributor or your coil is not getting juice or ground. You need to verify which this is before you bypass.

Then, if after all this you still have no solution say to hell with it and wire it direct to + power with an inline switch. If it still gives you trouble then you can always get an aftermarket crane or msd ignition box that is standalone.

I hope I've shed some more light on my previous comments.

Good luck

Pete

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