JD 4600 won't turn off

[tbrooks26]

As some of you know I've been working on this tractor for a little while in my spare time. Got some things fixed, got it running, but it won't turn off. I have to turn the fuel shutoff and wait for it to run dry. I talked to a guy at my local JD, who suggested a new solenoid, and said basically that was my only option other than rebuild. Well I have had the solenoid out a few times, and it seems to be working fine, and rotating the plungers properly. I have also tried rotating the plunger pinions by hand, and using an allen key with the solenoid removed, to press the lever inside. The plungers are moving freely. It has been sitting for over a week now soaking with some PB, but still no change. I'm thinking it must be something to do with how the plungers seal, to shut the fuel off. Which means it would be time for a rebuild. Maybe I can find a kit somewhere and do the top end myself. It doesn't look too hard, but it may require special tools. It would be nice to get this fixed without removing it from the tractor though. Any Ideas?

 

[davesl708]

I would agree the solenoid is not the problem. Solenoids should fail shut not open. Fuel is leaking by.

 

[tbrooks26]

I had a friend who knows a little more about diesels stop by n listen. He thinks my injectors aren't closing and its running rich. Might also be why it won't shut off?

 

[pat32rf]

Are you 100% certain that the voltage is being removed from the solenoid when you open the key switch? ALL of the voltage?

 

[tbrooks26]

I haven't put a tester on it, but removing the solenoid and using the Allen wrench in its place, or turning the plungers by hand eliminates that as the problem. Somehow fuel is still entering.

As I understand it when the plungers turn they create a bypass circuit for the fuel to return to the tank. So they are always pumping fuel. If the injectors are stuck open, then they might allow low pressure fuel to enter the cylinders. At least that's my theory, not sure if it is true

 

[tbrooks26]

Any other input on this? I'm really hoping/leaning towards the injector(s) being stuck open. I just think that after the trouble I had with the plungers being stuck, its logical the injectors could be stuck as well. Of course I have limited diesel knowledge, so I could be totally wrong. I haven't had time to work on it again. Not even sure what I should do with it, I don't want to keep running it. I know I can loosen the lines to isolate a bad injector, but I also know how dangerous high pressure diesel is. And if it is more than one injector it might not be so easy to tell. So far no signs of fuel getting into the oil.

 

[Billrog]

If the fuel solenoid is working it will shut off ...

 

[tbrooks26]

It is working, promise check this out
https://www.youtube.com/watch?v=ZusHCfOBmsg
Thats what happens just flipping the key on and off. The plungers won't rotate any farther. If not the injectors, the only other thing I can figure is seals in the IP

 

[tbrooks26]

Finally was able to get back to work on this guy. I just got some property so I've been focused on that for the past couple months. Today I went ahead and pulled the injectors. It was a pita, took most of the day. Had to tear the whole dash apart and remove the gas tank to get to them. They look pretty nasty, and took quite a bit of work with the slide hammer to get them out. Tomorrow I'll have to pick up something to soak them in. Hopefully I can get them cleaned up and working again. I guess after I get them back together, I'll take em to my dealer to let them test them before re-installing. Its my first time attempting this, but from videos I've seen, it shouldn't be too bad.

 

[Tx Jim]

I'll bet even if inj are leaking(not popping off correctly) that the injectors are not the reason engine won't stop running when key is turned to off. Engine not stopping is either faulty solenoid operation or faulty injector pump but not faulty injectors.