Hey all, this one is getting me. My fiberglass bucket has started running 30 seconds to a minute after you turn the key off. Its' not the out of time dieseling that some do, just it runs with the key off a while before shutting down. I've checked grounds and all seem to be tight. wiring is all new (car is less than 2 years old) Running a Mallory ignition system with mallory coil and ballast resistor. Anyone point me to the next things to check out to get it to shut off?
Actually not a bad thing if you’re running a Stromberg 97 or a Holley 94. And an electric pump. Both are known to weep after the engine shuts down from the residual pressure. The engine running for a bit after shutting it down relieves the gas line pressure.
Thanks guys, I'll look at the alternator and a diode, it felt to me like positive juice was leaking to keep it going, but haven't messed with this issue before
Just for the heck of it, try putting the key back in the ignitions switch and jiggling it towards the off position while it is running. If that doesn't do anything, I'm with everyone else that the alternator is feeding the ignition circuit with the key off.
A diode in the alternator will work. So will running it through a keyed relay. I smoked a diode because it was not of large enough capacity. The relay is reliable.
I had that happen when I installed an electric fan. When I put a relay in it solved the problem. I guess the fan spinning when the engine shut off generated enough juice to keep the engine running.
Agree it's likely feedback from the alternator ignition switched exciter wire, or could also be from electric fan turning and acting like a small generator. For the exciter wire just need a diode. For the fan, running through a relay or a diode will fix it.
Put it in the wire going to terminal #1, NOT the heavy "charging" wire that goes to the battery (or ammeter, or starter depending on how your car is wired).
I had the exact same problem. Electric fan wired into the "run" side of the ignition...without a relay. As the fan wound down, it would send power back through the ignition and keep the car running until the fan completely stopped.
While I'd jump on board with everyone else your wording has me thinking is this a new issue that never use to happen?
Thats an interesting possiblity, The new thing over the winter is a much larger electric fan. I havent tried running the car a short time before the fan kicks in and shutting it off. A relay is laying on the bench and needs to be installed, just had 100 other things i have to get done around the house too
There it is. The fan's motor as it spools down generates voltage that feeds back into the wiring loom. In this case the IGN curcuit.
Yep, @Johnny Gee I think that's the ticket, its the "new" thing on the car and seems to make just enough to bleed through. Ill have to put the relay to the top of the priority list.
When I was wiring my 56 I elected to not use a relay for cooling fan because it wasn’t link to IGN. While testing things before any start up of engine I’d turn the key off only to have starter throw out the starter gear (main power to motor removed). I added a relay and all fine. I no longer have a electric fan but not for that reason.
To rule the fan in/out, disconnect the fan (or pull the fuse) then do a run test w/o the fan to see if the engine shuts off properly.
If you're using a stock ignition switch ,all Tri-5's have continuity between the Ign and Access at the switch. So if you hooked up a fan off the accessory it could keep the engine running on. They are really easy to hot-wire at the fusebox Just bridge a wire from the courtesy lamp 12v live to any spare post on the accessory circuit , it will make it's way to the coil.
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