Ford 600 wont shut off with key.

crselsor

New User
My tractor is having a weird issue. It was running fine and I went to put some food plots in at the farm. About an hour into running the tractor it starting running rough and back firing. It was also lugging down and when I would give it more throttle it would take a while to catch up and almost cut out. Well I limped along to get finished and when I went to shut the tractor off with the key it kept running and really started backfiring and carrying on. I had to choke it out to get it to shut off. The tractor only seems to do this if it has been running for 15 minutes or more. I know I have heard of 12 volt conversions back feeding through the ignition if you don't put a diode or light in the wiring. The tractor had ran fine up until this day. Is it possible the ignition switch is shorted out and still making partial contact in the off position?
 
I suspect carbon build-up in the cylinders to the point that the carbon stays hot enough to keep the engine running even when it's getting no spark. Try pulling the high tension wire from the center of the distributor cap when it's running on like that and if it continues then it is definitely not an electrical problem.
 
Is it possible the ignition switch is shorted out and still making partial contact in the off position?

In addition to Sean's excellent advice, you could also electrically remove the ignition switch and use a jumper wire to act as an on/off switch.
 
If the exhaust valves are not closing properly because the lash hasn't been adjusted since 1960 something, the edges can get hot enough to be like little glow plugs just like carbon as mentioned below. One of my pet peeves since starting working at the dealership in 1984 the tendency for people to spend money throwing parts at a poorly performing tractor from tune up parts to 12V conversions, electronic ignitions, etc. ad nauseam, but won't check their valve lash.
 
Set the idle speed to factory spec., 400 RPM or so.

Turn off the ignition only after reducing engine speed to idle.

Dean
 
(quoted from post at 07:18:40 10/20/18) Set the idle speed to factory spec., 400 RPM or so.

Turn off the ignition only after reducing engine speed to idle.

Dean
Normally, Dean, I think your comments are pretty good advice. This isn't one of those! "Tractor running well then started running poorly and won't shut off" doesn't lend itself to thinking the OP is doing the shut down process improperly in my mind.

Others have given good advice. I can also see both the OPs issues generated by a slip in timing somehow.
 
Gasoline engines will often run on if the ignition is shut off at speed, especially if the throttle is not closed or the throttle shaft and/or bore is worn allowing air to pass by the throttle plate.

No, this is not the only reasons for run on but the solution is very easy to implement.

Dean
 
I always idle the tractor down to 450 rpm before I attempt to shut it down. Regardless, the problem still happens at 450 rpm. The only other thing that I did to the tractor that I forgot to mention is replace the governor compensating spring that attaches under the battery box. Before I did this I had to constantly keep my hand on the throttle lever to keep it from backing down all the time. Could this have anything to do with it.
 
I will get the tractor out of the garage later on today and run it around the yard until it is up to operating attempt and try and shut it off and if it doesn't I will pull the high tension wire and see if that kills it. Will let you know what I find out. Thanks for the help
 
I got the tractor out today and drove it around a while. I also tried shutting it off soon as I started it and it still stayed running. Then I got it up to temp and tried shutting it down. It wouldn't die just kept backfiring. So when it was doing this I pulled the high tension wire off the distributor cap and it died immediately. So this leads me to believe it is an electrical issue.
 
(quoted from post at 13:19:28 10/19/18) My tractor is having a weird issue. It was running fine and I went to put some food plots in at the farm. About an hour into running the tractor it starting running rough and back firing. It was also lugging down and when I would give it more throttle it would take a while to catch up and almost cut out. Well I limped along to get finished and when I went to shut the tractor off with the key it kept running and really started backfiring and carrying on. I had to choke it out to get it to shut off. The tractor only seems to do this if it has been running for 15 minutes or more. I know I have heard of 12 volt conversions back feeding through the ignition if you don't put a diode or light in the wiring. The tractor had ran fine up until this day. Is it possible the ignition switch is shorted out and still making partial contact in the off position?

Yes... it possible..

Its also possible for the selonoid to have stuck in the start position, and run down the battery.

Its possible the carb float stuck and it carboned up and started dieseling.

Its possible the alt has a back feed, for whatever reason and supplying voltage...
 
(quoted from post at 18:16:20 10/20/18) I got the tractor out today and drove it around a while. I also tried shutting it off soon as I started it and it still stayed running. Then I got it up to temp and tried shutting it down. It wouldn't die just kept backfiring. So when it was doing this I pulled the high tension wire off the distributor cap and it died immediately. So this leads me to believe it is an electrical issue.

Still makes me wonder if the timing has slipped or the advance mechanism has failed.
 
Do you have a test light? When it runs on see if there is power at the coil primary terminals. If so it's a problem in your primary wiring. If you have an alternator disconnect it and see what happens. If there is a diode inline it might be going bad.
 

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