no spark from coil sometimes

[95mystang]

I'm having a no start problem. Here it is I changed everything, plugs, wires, cap, rotor, coil. I had the module tested checked out okay. Still sometimes when I go to start the car, it just won't!!!!! I'm getting power to the coil, but still nothing comes out. NO SPARK Please tell me whats going on here. Is there another reason that trhe spark isn't coming out of the coil?

[PKRWUD]

It's really a pretty simple system. The coil only requires a 12 volt power supply from the ignition switch, and a pulsed ground signal from the TFI module. You've verified the power supply to the coil, and you have replaced the coil. This leaves the TFI module. Unlike the coil, TFI modules can work intermittently. A coil is like a light bulb: it either works or it doesn't. If your problem occurs more often when the vehicle is warmed up, like when you go to start it after getting gas, then I am certain the TFI module is your problem.

Take care,
-Chris

[DRASTiK]

I agree with the above comments. I had this problem a while back and PKRWUD was there for that too. I replaced all kinds of stuff, even the TFI, and still had the problem. 9 out of 10 times, it will be the TFI. The other time (at least for me) it can be the PIP inside the dizzy. That can also die intermittently. It took one of those expensive high tech scanners and a kick *** voltmeter to pick up on these for my car. My home scanner didn't pick up on it at all. Good Luck,
Dave

[DRASTiK]

oops, double post. Sorry

[No Groc Getter]

If it is an aftermarket ignition (MSD etc) that you wired in yourself, check and make sure the ground to the chasis is clean and tight. Even scrape some paint under the connector to be sure.

Going back to the TFI angle. I've had new out of the box TFI modules that would not fire my car.

[jetuomi]

ok, I HAD THE EXACT SAME PROBLEM!

mine first started when the fuel pump started screaming, so I got that changed..

Then, it wouldn't start, so I got a new TFI..

but then sometimes it would just stall.. that problem was the distributor point, sometimes the coil would put out a spark, sometimes not.. SO, I'd check the TFI and/or the point.

Good luck !!