John deere 120C SN FF120CX035538 My John Deere 120C Idles rough when it gets to normal operating temp but runs smooth on start and then slowly gets worse as it comes up to temp. it chugs like its missing or sucking air. I have replaced all the injectors and the fuel lines going to them as well as the injection pump (I have double checked that its timed correctly with the pin tool) I have replaced the cam timing sensor and the timing sensor on the hydraulic pump as well as multiple other sensors dealing with heat I'm Hoping for some suggestions Thanks! Nate
Good job on providing the serial number. Stupidly I ask have you ruled out air intake restriction to the motor. Next stupid question is what have you done to make sure it is not contaminated/dirty fuel/algae. Does the fuel tank have a drain and when was it last drained to clean out the crap in the tank. Did this happen at one time or has it slowly gotten worse. Some of the smart folk on here will be along shortly to give you much better advice/options.
So you have spent how much to date with no results?
I'm not familiar with the JD120 but am assuming it's a common rail fuel system. If so does it have a Can Bus wiring system? If so check that wiring from the ECU to the PVC, particularly near all plugs and insure its getting proper voltage above engine idle. The reason for asking these questions is that a JD 4045 engine started doing the same a similar thing. I checked the exhaust manifold temps and #1 cylinder was running cold, JD tech came out, did an analysis and confirmed crook injector, new injector $1400 and no change with the problem. Tech came out again, diagnosed crook rail pressure sensor $600 no difference. The owner sold that machine for cheap, new owner gets in an Auto Lecy, in 15 minutes finds a partly broken canbus wire ,repairs it, problem gone.
Have you tried running it off of a Jerry can of fuel to see if it will perform. Need to do simple things for no money before buying expensive parts. Has it been run with fuel cap off and rag tied over opening. Simon C
This gives me some things to try. I'll let you guys know what happens. Thanks!
It has. for a matter of fact it started happening after the fuel cap was lost
What is an auto lecy?
Auto electrician in Oz.