John Deere 4720 running rough

[arlen4720]

but it does.. not the turbo, but the fuel injection system works that way, I already posted the link here that shows this.. ok, here it is.. Common Rail Injection System Pressure Control

I don’t want to derail the OP’s thread any more than necessary...the example you linked is not at all how the fuel injection system works on a 4720...not even a little bit. It’s not a common rail in that sense. It has a separate “unitary injection pump” for each cylinder.
Further, even in your example there are no sensors that look at mixture...at least none that I could see.
The normal sensors that diesels need are throttle position and engine rpm.
I will post some excerpts from the tech manual when I get time. Maybe some possible causes of the OP’s problem will jump out.

 

[radios1]

I don’t want to derail the OP’s thread any more than necessary...the example you linked is not at all how the fuel injection system works on a 4720...not even a little bit. It’s not a common rail in that sense. It has a separate “unitary injection pump” for each cylinder.
Further, even in your example there are no sensors that look at mixture...at least none that I could see.
The normal sensors that diesels need are throttle position and engine rpm.
I will post some excerpts from the tech manual when I get time. Maybe some possible causes of the OP’s problem will jump out.

ah! now I see what you are trying to do!. have at it, since I'm out of this thread!..

 

[thepumpguysc]

If you've changed the lift pump already & ran it w/o the air cleaner..
THATS about it.. other than going into the engine for pump & injector work..
Check the push rods & see if they're bent..

 

[Dci]

Any info on a good place to take it near Yulee Fl? The Deere dealer in Jacksonville and Mershon Ga. I have little faith in.

 

[thepumpguysc]

Seeing its prob. gonna boil down to pumps & injectors.. look around your area for an INJECTION PUMP SHOP..
A LOT of them have a drive-in/drop-off service bay.. & are very familiar w/ the JD's.. it never hurts to ask first tho..
Just tell'm u have a JD 4720 w/ Stanadyne unit injectors & pumps, under the valve cover.. & u need to know if they have experience in diagnosing & replacing them.. & IF they send u to JD.. ask them which one THEY recommend.
1 more thing>> those pumps & injectors are NOT rebuilt.. new only.. & you'll be 100's of $$ ahead buying them yourself thru a pump shop than paying JD to mark them up..

 

[Trainpilot]

I'm hoping the OP will tell us what the outcome was. I have a 4520 (same series) that is one of my favorite tractors. It is showing error code 207 and is only starting intermittently. When it starts it runs fine. JD tech spent over an hour hooked up to it with a couple of black boxes. Said he needed to talk to JD central re:diagnosis. 4 days later, I was told it needed a new computer to the tune of $2000 plus labor. OUCH! I'm trying to learn all I can about this tractor, and have not yet bit the bullet on a new controller.

 

[jkflatt]

wondering if this issues was resolved and what the fix was? May have similar issues. Thank you.