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Engine not turning off.....
pekwah1 - 29/5/11 at 04:08 PM

Hi Guys,

just a quickie, when i turn off my ignition, the engine keeps running.
It's a sylva striker with a 1300 xflow.

Now also when the engine refuses to die, it also still runs after i completely disconnect the battery.

So, i'm assuming it's running from alternator power alone, but how is this possible if the battery is unplugged?
My alternator actually is hooked up on the positive terminal for the starter so i'm guessing this might be travelling down the wires and somehow keeping it live....

Suppose this would be easier if i just made a loom, but no i was lazy and bought it from raw instead.....

Cheers,
Andy

ianclark1275 - 29/5/11 at 04:34 PM

correct the alt is powering the ignition.

trace live feed to coil back to the ign switch.

IC

rusty nuts - 29/5/11 at 04:38 PM

Sounds like there is still a feed to the coil positive when the ignition is turned off? Time to get the multimeter out and start checking, could be the alternator is feeding back through the ignition switch? Disconnecting the battery with the engine running may damage the alternator so not a good idea. What ignition switch are you using?

stevebubs - 29/5/11 at 05:12 PM

I would take the alternator directly back to the battery positive rather than use the starter connection.

JAMSTER - 29/5/11 at 05:13 PM

it could be that you cooling fan is running all the time?????????

i had a car that done this

austin man - 29/5/11 at 07:50 PM

definitely a live back to the ignition I have seen Rad fan , dynamo and alternator do this

BaileyPerformance - 29/5/11 at 08:50 PM

quote:
Originally posted by pekwah1
Hi Guys,

just a quickie, when i turn off my ignition, the engine keeps running.
It's a sylva striker with a 1300 xflow.

Now also when the engine refuses to die, it also still runs after i completely disconnect the battery.

So, i'm assuming it's running from alternator power alone, but how is this possible if the battery is unplugged?
My alternator actually is hooked up on the positive terminal for the starter so i'm guessing this might be travelling down the wires and somehow keeping it live....

Suppose this would be easier if i just made a loom, but no i was lazy and bought it from raw instead.....

Cheers,
Andy


Hi, a quick way to sort this problem is to install a diode in the alternator warning lamp wire (the small wire on the back of the alternator) Buy a 3A diode from Maplin Order Code: QL81C, white strip on diode towards alternator. (must be right way around)

daviep - 29/5/11 at 09:17 PM

quote:
Originally posted by stevebubs
I would take the alternator directly back to the battery positive rather than use the starter connection.


Why what's the difference?

Davie

snowy2 - 30/5/11 at 07:05 AM

quote:
Originally posted by stevebubs
I would take the alternator directly back to the battery positive rather than use the starter connection.


Almost every car ever made uses the live feed to the starter as the connection for the alternator, it would not make the slightest difference to the problem stated above moving it*. i suspect that the coil has a permanent live feed, rather than a switched one. The car continuing to run even after the battery has been disconnected indicates this. If your car runs any sensitive electrical devices (electronic ign. electronic dash) disconnecting the battery could cause a massive voltage spike which could kill them all, the battery acts like a voltage stabiliser. The alternator is also not going to like it much either, and it could blow the regulator pack.

* besides it really isn't good practice to have numerous connections on the battery, ideally there should be only one live and at most 2 earth's.

[Edited on 30/5/11 by snowy2]

steve m - 30/5/11 at 07:49 AM

But surely the ign + side needs to go throught the ign switch, thus key off means no + to power the coil ?


Also it seems that the ignition is ALWAYS on,


Well, thats how mine is done!

Steve

omega 24 v6 - 30/5/11 at 11:24 AM

Feed back from the alternator. many of us have had it and the diode does cure it. Basically when the alt starts charging it puts a pos down the thin w/light wire line ( so there is no longer an earth to make the light go on. When you turn the key off with the engine running this pos then goes through the bulb and even with the resulting voltage drop ( the bulb being in series) sometimes there is enough voltage ( 3 to 5 volts or more) to keep sensitve electronic ( read ecu) devices powered up.