Ignition switch? Won't start

[Moose]

I drive a '78 Bronco 400 w/auto trans

It turns, but won't fire over.

Last friday, I went to drive home from work, so I go to turn the key and smell something electrical burning. I even think I see a cloud of smoke come from under the dash board.

I checked my fuses under the dash, fine. I've checked my plugs, even done a spark test. I've checked everything around the selinoid and accompanying fusible links, fine. I've checked all the vaccume lines in the engine compartment, fine.

A friend at work told me about the actual wire harness that goes to the ignition switch. He said sometimes they burn out. I have a spare ignition switch I can swap out, but has anyone heard of this. I haven't checked any relays. Any thoughts anyone?

[BroncoJo]

Did you check the siliniod?

[Moose]

No because it's new. But I can check it to make sure. I'll get back.

[stx4wheeler]

Mine does cool stuff like this enough that i dont worry about it to bad usually it is the solenoid on the firewall, it usually happens when i go to crank the truck, and the battery is low. Replace the five or 8 dollar solenoid and maybe charge the battery some if it seems low.

p.s we ever gonna get to see this bad boy bronco in action? TCC maybe

[stx4wheeler]

Also if you go to advance autoparts you can prolly just take your old one in there and say it is under warranty with Texas A&M off-road or A&M off-road, and get one for free, cause i bought mine under the club account.

[sasquatch]

if its turning over then the starter is working and its not the starter solenoid. check to see if you are getting spark. do you have electronic ignition? if it was the ignition switch or wires associated, you wouldn't get power to the coil.

[Moose]

if its turning over then the starter is working and its not the starter solenoid. check to see if you are getting spark. do you have electronic ignition? if it was the ignition switch or wires associated, you wouldn't get power to the coil.


I finally got another chance to play with it. After buying a new dohikey that I can check for spark w/out having to use jumper cables to ground the spark plug. Anywho, I don't have spark now.

But I also wanted to see what you meant by, "do you have electronic ignition? if it was the ignition switch or wires associated, you wouldn't get power to the coil."

I do have electronic ignition, but all that stuff is new: MSD6A box, MSD offroad high vibration coil, wires, gapped plugs, distributor cap and rotor. only thing in ignition that is stock is the actual distributor (by the way, sometimes, i can floor the gas pedal and the carb will backfire... distributor broke?). I kind of get what you are saying. But it's turning, therefore the switch must be ok, so the problem's somewhere between the plugs and silinoid?

[Fredo]

make sure the MSD box is working. I've heard of more than a few of those just crapping out like someone just flipped a switch.

[Moose]

i checked the spark from the plug wire at the coil end, no spark. then hooked a 12V tester to the positive side of the coil and grounded the tester to the negative post of the battery like the manual said. no power there either.

your are the 10+ person that's said that about the MSD boxes. How do I physically check the ignition box? Or does anyone know where I can get a good deal on a Mallory unit? maybe Accel? I haven't had the best of luck with Accel. But nothing really terrible. Anyone heard anything about DUI (Davis Unified Ignition)?

thanks yall

[Sharpe]

Remove the box from ignition circuit. If truck worky, that means box no worky.

[Moose]

I got her runnin. I did all the trouble shooting stuff. I'm just too shade tree to even be doin that right. So, I just started replacing stuff... and it paid off for once.

At first, I wasn't going to tell anyone I changed the Stator inside the distributor because of how smooth it runs now than before with the MSD Coil and 6A Ignition Box. But, somehow I won't put 100% of the blame on MSD. However, because of the smoothness, how well it responds to throttle, and starting cold after sitting for 3+months, I have to say, leave well enough alone.

All I really did was change back to stock coil and Ignition Box. I'm going to have it mounted with rubber gromets as shocks.

The one thing I did extra was change out the Stator. I don't know how you can tell if those things go bad, because I don't see anything "fried" on it. But, it did look a lot corroded and brown. I almost fell for the DUI distributor, and I may still in the future.

What's funny is, like I said about the new found throttle response; it used to backfire through the carb with the MSD. When cold, I'd tap the gas about an inch or two into the pedal to warm it up, and the carb would backfire. Also, when it was cold, if the idle wasn't high enough, pulling out of the office parking lot, she'd die as I drove out. But now, after the very first fire, she didn't spit back not once... which says I must have had a timing issue... and maybe the stator in the distributor atually was bad???

Now, I've just got to fix the wiper motor, brakes, & horn and I can drive her again.