Northy
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| posted on 15/7/04 at 10:56 AM |
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Alternator causing engine to keep running
Can anyone help? When I try to stop the engine it keeps running. I've narrowed it down to something to do with the alternator, see "Help!
Engine won't stop!" in the Engine and Transmission section for full story.
Can anyone help? Is this a faulty alternator?
Cheers
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing! 
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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Terrapin_racing
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| posted on 15/7/04 at 11:21 AM |
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Seen this before - problem with the engine continuing to run when the ignition key was removed from the lock. This was caused by the alternator
feeding back through the ignition system. There should be a DIODE in the alternator to prevent this. Check with your alternator manufacture (or a
local auto elec) to see if the diode is build into the alternator (and has failed) or located somewhere else in the circuit.
Best of luck
Rob
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David Jenkins
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| posted on 15/7/04 at 11:45 AM |
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In the same vein, it's also worth knowing that alternator diodes are extremely vulnerable - they can be blown by running the car without the
battery connected, or by welding anywhere on the chassis (if you're unlucky).
Any auto electrician can check it, and in most cases it's not an expensive item to fix (if the diodes are replaceable, that is)
rgds,
David
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theconrodkid
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| posted on 15/7/04 at 12:22 PM |
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have you got an ignition light???it rings a bell from my banger racing daze
who cares who wins
pass the pork pies
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Northy
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| posted on 15/7/04 at 05:13 PM |
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Cheers guys I'll have a look tonight.
Conrod, yes, I've got an ignition light, can't remember if it was working or not though. What are you thinking?
Cheers
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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theconrodkid
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| posted on 15/7/04 at 05:53 PM |
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built a racer once and some clown wanted the dash,dash was removed along with all the lights,engine wouldnt stop when it was turned off,wired an ign
light bulb in the circuit and it turned off,worth a try???
who cares who wins
pass the pork pies
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Northy
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| posted on 21/7/04 at 09:07 PM |
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Right, I got a replacement alternator and fitted it tonight and.....
......it did the bloody same! 
What are the chances of getting two duff alternators?
I think I've wired the bloody thing up correct, switched live from ignition to one side of the charge bulb, other side of bulb to the exciter
terminal on the alternator. Is that right? 
Can I just stick a diode in the wire behind the dash? That'll do the same job won't it?
Do I actually need an alternator sor SVA?
I really need help on this one guys...
Cheers
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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hortimech
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| posted on 21/7/04 at 10:00 PM |
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what sort of alternator is it? a lucas or something else
Why does everything happen to me
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JoelP
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| posted on 21/7/04 at 10:04 PM |
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lucas lra 101 apparently.
as said in chat graham, try unplugging the warning light whilst it is runnign with the ign off...
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Northy
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| posted on 21/7/04 at 10:06 PM |
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Yeah, Lucas LRA101
AKA, the bag "o" shite alternator
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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hortimech
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| posted on 21/7/04 at 10:14 PM |
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if removing the bulb stops the engine, then problem is most likely upstream from bulb holder, probably either inncorrect wiring or faulty ign
switch.
we get a similar problem at work, but in our case the battery goes flat over night due to drain through ignition switch. well at least I,ve learned
something from this, dont use a lucas alternator. the method of wiring to it must be the stupidest way possible
Why does everything happen to me
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Northy
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| posted on 21/7/04 at 10:16 PM |
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How should it be wired?
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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hortimech
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| posted on 21/7/04 at 10:24 PM |
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If that comment was aimed at me, then how about with three wires
1 big thick output wire
1 switched 12v exciter wire
1 0v wire going to bulb in dash, when alternator starts charging this turns off and light goes out. if bulb blows it still keeps charging,
lucas's way if bulb blows, no charge
Why does everything happen to me
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Northy
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| posted on 21/7/04 at 10:27 PM |
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Yeah, sorry was asking you!
There are three terminals, To big ones that go to the battery and the exciter.
I'm confused now....
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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hortimech
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| posted on 21/7/04 at 10:41 PM |
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dont be, the alternators that i am refering to, are very small ones made by nippon denso if I remember right and used on F1 cars (so I'm told)
amongst others. I just think the lucas way of wiring up alternators is stupid. If when you turn off the key your engine does not stop, it must be
getting power from somewhere. the only way to trace it, is to work backwards from alternator, check all connections, wires, etc until you get to
ignition switch. If you cannot find anything wrong with any wiring or switches etc it must be the alternator you have just fitted. I still think the
main suspect is the ignition switch, but it is hard to diagnose a problem from a distance.
Why does everything happen to me
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Northy
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| posted on 22/7/04 at 07:00 AM |
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OK, cheers
I tried the car with the alternator unplugged and it stopped fine. Thats why I thought it was the alternator.
Oh how confused am I now?
Can somebody tell me how this bloody thing is supposed to be wired?
Cheers
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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JoelP
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| posted on 22/7/04 at 07:21 AM |
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have you tried unplugging the exciter to stop it running? is it stops then the exciter is wired in wrong,.
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theconrodkid
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| posted on 22/7/04 at 07:26 AM |
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where on the ign/sw is the take off for the ign light?some stitches have 2 terminals bridged inside
who cares who wins
pass the pork pies
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Northy
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| posted on 22/7/04 at 12:10 PM |
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Cheers for the suggestions so far guys, I'll have a play tonight.
Conrod, its just to the switched live circuit. Without the engine running, when you turn the key forward to run the exciter wire goes live, when you
turn it back to stop, it goes dead as it should. Shitty things only start happening when the engines running. I'm almost 99% sure the alternator
is backfeeding, what do you think?
Cheers
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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theconrodkid
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| posted on 22/7/04 at 12:33 PM |
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try with no fan belt on,deffo sounds like it
who cares who wins
pass the pork pies
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Northy
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| posted on 22/7/04 at 09:17 PM |
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Right, tonight I fitted (bodged) a diode into the exciter wire, and guess what, the engine stops! Yeah!
So I've soldered it all in nicely. Job done hopefully. I'll maybe have a go at testing the alternator after the pressures off a bit. SVA
two weeks today!!!! 
Thanks for you help guys.
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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theconrodkid
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| posted on 22/7/04 at 10:21 PM |
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glad to hear it,check watage of the bulb ,should be 3 or 4 i belive
who cares who wins
pass the pork pies
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