Won't stop running even with key out...

[Snowblind]

Hopefully somebody has seen this before. Turned off my truck ('77), had key in hand and heard this slight rumble and realized my truck was still running. Put the key back in and turned it off again without a change, went thru the gears and nothing would turn this thing off. Decided to pull the coil wire and undo the battery. Connect the coil and battery up again and it starts no problem just doesn't want to stop running.
I'm thinking the ignition switch but wanted to check here first in case there's a different solution.

Thanks,

SB

 

[swa0330]

Sounds about right. LIke you're not closing the electrical loop via the ignition switch. It's not the starter solenoid, cause that's always the endless starting problem. I don't know about ignition switches a whole lot, but I cannot think of where else the problem would be. Fire and fuel are the only things that run a gas motor, so maybe you could use that for your diagnosis.

 

[eb66to77]

Is this something new? It is probably the ignition switch since it stops when you pull the coil wire.

 

[Broncobowsher]

Probably the switch. Tried going to acc and see what it does?
Another possible thing is a voltage regulator messed up, feeding power back where it shouldn't be. Please do not try and connect or disconnect this while the engine is running, they tend to fry from the spikes. Try disconnecting it, starting and stopping. If it does stop, bad regulator. If it keeps running probably the ignition.
Also try pulling the "I" wire off the starter solenoid. That is the last chance for a non-ignition switch problem. That would be a bad starter solenoid. If it isn't the Ignition switch, voltage regulator or solenoid, then start shopping for a wiring harness as you have a short in there somewhere.

While thinking of it, any other accessories that may have been tied into the ignition and a constant power wire need to be checked as well.

BTW pulling the coil wire will stop the engine even if the key is working right. Spark iginition engines don't run very well without spark. Battery is a safe disconnect as well as the power is still on to something that it shouldn't be.

 

[elemetal]

Put a volt meter on any hot wire in the ignition loop (I wire as stated above, + wire to coil, etc) and turn the key switch on, then off. You should see a correllative change in the voltage (12 or 0). If it doesn't do this, the problem is the switch. You don't need to have the vehicle running. If you have any voltage when in the "off" position you have a bad switch or a wire fused somewhere to an "always powered" wire (unlikely).

 

[Snowblind]

Ya, this is fairly new, happened once a few weeks ago and now it happens all the time. When I put the key back in, nothing happens as I rotate thru the switch (acc, on etc). One thing I noticed was the other electrical items shut off (stereo, lights etc) but the engine just keeps going and going. I'll do some of the trouble shooting suggested, thanks.

SB

 

[Skuzzlebutt]

Probably the switch but when mine did this last year I could unplug the switch and the Bronco still ran. There was a short in the harness I never did find. Installed a Centech to fix it.

 

[Snowblind]

Well things just got more complicated. It started fine but made an awful noise, kind of like the starter stuck so I pulled the coil wire and it still ran but then died when I disconnected the battery. Seems the problem is bigger than just the ignition switch unfortunately. Guess the harness is thirty years old and could you replacing.

SB

 

[eb66to77]

Did you make any changes to the harness?

 

[Snowblind]

Nope, my truck is extremely stock except for a stereo I put in two years ago and an Edelbrock carb and intake a few months ago. The harness is original and complete without any PO issues. I think I'll start by changing the ign. switch and go from there, here's hoping!

SB

 

[DirtDonk]

But you're not sure that it was the starter stuck on? If the engine would keep running, and now the starter stuck in start, then it could still be the ignition switch, but also be a starter relay/solenoid too, as was mentioned before. Not only does it control the starter but also sends a jolt of 12 volts to the coil during the start process. If that circuit (the "I" post on the relay) stayed energized for whatever reason, your engine would keep running.
Maybe just a simple continuity test to see if the circuit is closed between the two big posts and that one little one on the relay?
Can't hurt to check before digging deeper into the wiring.

Paul

 

[braxton357]

Is it dieseling? Like kind of a slow knock rather than just idling? Which coil wire are you pulling? The ign hot, coil ground, or the actual high voltage coil wire?

 

[taipeichris]

I had this problem twice and fixed it both times.

1st time, my wire harness was melted and the circuit to the alternator wasn't getting turned off. It's not the started. The starter gear will only engage the flywheel only when starting. Check the ignition switch, coil, voltage regulator, alternator, but if you have tectonics electronic points my money would bet on that! When they die the do odd things.

2nd time, I finally installed a new Painless wire harness and came up with the exact same problem again. This time everything was new and it still did it. Guess what! The Painless instructions were wrong on the alternator wiring diagram! I went into my Mustang shop manual and wired it accordingly. It's never miss behaved again. In the future try to find electrical parts with “lifetime warrantees”.

Keep photo copies of receipts, the original will fade over time, and next time just exchange them against the warranties. I've saved myself a lot of cash this way over the years. If you are still having problems give me a ring on a Sunday!

 

[Snowblind]

To answer Braxton357, with the key out, the truck runs exactly as it does otherwise nice and smooth and I could keep driving like that until the noise I got yesterday when starting. I pulled the coil wire that goes into the distributor cap. I'll take the ign switch out this morning and see if the local parts stores have one and go from there.

Thanks to everyone for the advise, I've got plenty to go with now.

SB

 

[Snowblind]

Got a new ign switch but don't know if it fixes things as when I tried putting the pos battery cable back on the battery, there were small sparks and hissing/burning/melting type sound and once the truck tried turning over. I disconnected the voltage regulator but same issues with the battery so I didn't dare try the ignition. Guess I'll get a new starter relay next.

Any other suggestions,

Thanks,

SB

 

[oldiron]

I'm going to bet on the solenoid being bad. Just my .02.
Greg

 

[Snowblind]

Well, I guess I should of bought a solenoid yesterday when I picked up the new ign switch cause I got one today and everything seems to be back to normal.

Thanks again for everyone's help, now I have no excuse not to make it to work tomorrow ;D

SB

 

[oldiron]

Glad to hear it worked out well.;D
Greg