john deere 4200 will not throttle down

chopsrdown · Sep 24, 2014

I was given a john deere 4200,14 years old, sat outside in the weather the last 4 years without being run,races and will not throttle down.Trying to go through it to see if everything still works but when I start it the motor just races and will not throttle down.The linkage all moves.Key will not shut it off,have to shut of the fuel and let it run out of fuel.Any ideas?

puckgrinder85 · Sep 24, 2014

Sounds like injection pump issues to me. If it were some other flammable liquid feeding the engine it would likely keep trying to run if it had enough to do so. If you can kill the engine with the fuel shutoff its due to getting too much fuel somewhere down the line. Its kind of funny the key wont kill the engine as im sure its trying to energize the fuel shutoff solenoid, maybe those two problems are hand in hand as the solenoid will be on the injection pump most likely.

Firefita88 · Feb 7, 2015

Hey Chopsrdown - I'm having the exact same problem with my JD 420 and was about to check the linkage which feels tight and not sloppy. Would you mind sharing what the outcome was on your JD. Thanks

Egon · Feb 7, 2015

Does the fuel solenoid click when the tractor is started? Perhaps the solenoid is stuck open?

Is there a little spring on the throttle control by the injection pump?

Chances are you could stall it to stop it.

Google jd 4200 and you can find parts list and diagrams. The spring I mentioned is part no 15.