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tractor still runs with ignition turned off

W

Wayne D. Teel

New User
I purchased this tractor (1947 8n) about a year ago and I noticed that when the key is turned off while it is running above idle it still keeps running just fine but when I drop the throttle down to idle it will shut off. What is going on here. This tractor was converted to 12v system. I haven't tried to trace it down yet but was wondering if any of you have a suggestion of waht the problem might be.
 
Probably a bad ignition switch,has low grade short int it,keeping the circuit closed. Other possibility is that there is a wiring problem
 
You have a wiring problem. The alternator is powering the ignition. Probably need a resistor in the line to the alternator exitation.
 
Very common problem is someone stuck a Delco 10SI or 12SI alternator on there with a two or three wire hookup. The excite circuit, if hooked to the ignition terminal of the swith, backfeeds power from the alternator and stops you from shutting it off when the alternator is charging.

Just add a 50 watt diode in the excite wire and it stops the problem. Or, if you have an automotive type switch with an IGN and a ACC terminal - use the ACC to excite the alternator and the IGN for ignition. That way, no diode is needed.
 
If the conversion uses a delco internal regulator alternator, disconnect the plug to the regulator while it is running with the key off. If it stops, your alternator is backfeeding juice to the coil thru that circut to your coil. I had that problem and solved it with a relay that cut this path when the key is off
 
(quoted from post at 14:03:59 02/25/10) If the conversion uses a delco internal regulator alternator, disconnect the plug to the regulator while it is running with the key off. If it stops, your alternator is backfeeding juice to the coil thru that circut to your coil. I had that problem and solved it with a relay that cut this path when the key is off
Click to expand...

Not a good idea to remove the connector plug with the engine running. Depending on what regulator is used you are most likely disconnecting the voltage sensing wire which will cause the alternator to go to full output. Probably won't cause a problem for short time but a safer way is to remove the plug before starting the engine.
 
It"s backfeeding from the alternator. I had the same problem with a NAA several years ago. All I had to do was change the bulb on the dash. I don"t know if the 8N has the same setup. You may have to use a resistor. Some in this forum or the 8n9n2n forum can tell you how to correct it.
 
You asked that down in the N forum what didn't you like the answers there or have you not checked them because I know you have at least one or more when you first posted it. No I'm not being mean just saying you should look at your first post
 
When you idle it down, it dies because the alternator output drops enough that the backfeed ceases. Mine would keep running, so I just put in in third gear and let the clutch out. That killed it and solved the problem temporally. Sure beats unplugging the alternator and risking diode damage.
 
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