4120 Shuts down while operating

[beenthere]

Clean the fuel line and fuel tank. Check fuel line for crud or breakdown of hose material. For starters..

 

[kwbretired]

Check the fuel cap to make sure the vent isn't plugged.

 

[dothatagain]

Hello;

I have a JD 4120 W/ Power Shifter bought new six years ago. Over the weekend i started having problems with it just shutting down, like when you get off the operator seat while in gear.

After jiggling the power shifter or the PTO button, it will start again, this went on for a long time but only while and each time the tractor was in motion.

I think it might be a safety switch, anyone else have something like this happen?

Thanks
Jv

My 4120 was also stalling at random times; complete power loss. A hard hit on the dash would restore power most of the time but depending on the day it might try to shut down 12 times in a row or not at all. I finally tore into the dash. When I did this, I couldn't get any power to the starter. After reading other posts on this forum, I turned on the lights and attempted to start; it cranked but wouldn't turn over, just as reported by another person. I continued to check electrical connections and eventually found a connection behind the dash that was apparently loose enough have caused all the problems. It appeared to be a good connection, and all of the clips were still in place. I just pushed it tighter, and this seems to have fixed my problem. Getting behind the dash was a headache, but this ended up being a no cost repair.

 

[beenthere]

Sounds like you have it fixed.
Welcome to TBN, and good to have you letting the forum know your results.

But am some confused:

cranked but wouldn't turn over

That to me is an oxymoron.. if it is cranking, then the engine is turning over. Maybe not running, but at least is turning over.
Or are you saying the engine is locked up?

Or have I been missing something over the last 70+ years.