John Deere 6415/4045 engine running rough, need help!

HTEoregon · 2024-04-04T05:01:02.000Z

Got a call from a customer the other day and have been tinkering on this tractor since. I would appreciate any advice from anyone with experience on this engine. Engine runs, idles fine. Idle is a bit rough. When throttling engine up slowly engine runs very rough, sounds and behaves similar to air in fuel. When snapping throttle quickly it seems to sound fine revving up. Checked pressure and fuel flow at line to water separator from tank, my fuel gauge shows vacuum as well. Gauge read 0psi, no restriction from tank. Fuel sight glass shows no air. Checked pressure and fuel flow at line to primary fuel filter. Primary filter is post water separator, with the electric lift pump plumbed between the two. Fuel pressure pegged my gauge at 70 psi and again no air in fuel sight glass connected to fuel gauge. Replaced fuel filters. Removed fuel hard line from Primary filter housing to injection pump and found one of the seals in terrible shape. Replaced both fuel line seals. No change. Removed and cleaned screen on injection pump. Removed and inspected check valve on return fitting from injection pump. Clean and operational. Replaced o-rings under screw on caps on top of filter housings to eliminate them being a possibility. Replaced fuel return nozzles and seals due to some suggestions on other forums I read. Supply pressure seems to be more than enough. Can't see air in fuel. Fresh diesel. This tractor does not sit during off season, they run it consistently. He was mowing his pasture when this started suddenly, no warning. I noticed tonight the glow plug light is blinking, not sure if that's related to this issue or not. I just want to make sure I dot all my i's and cross my it's before I commit to pulling and pop testing injectors and running over head on motor. When bleeding injection lines each cylinder dropped off the same as all the others. Would expect to not hear a difference in one if there was a dead hole. Does anyone here more familiar with these tractors/engines/fuel systems know if there's anything I've missed on this machine? I would like to be sure I've exhausted all options before telling the customer we gotta go deeper! Thanks!

morrisfarmsNew MemberApr 6, 2026#21

PART NUMBER: RE207311 IS THE ELECTRONIC PART FOR THE ROUGH RUNNING. THE A17 TERMINATING RESISTOR FAILED CAUSING A LOSS OF COMMUNICATION FROM THE BCU. TRACTOR SERIAL NUMBER: LO6415A365991. Attempted to connect to service advisor to recall codes. Unit would connect but only to the ECM and would not read the BCU. Removed left side console panels and panels behind seat. Checked power and ground to the BCU. Removed and replaced the A17 Terminating resistor. BCU 639.19 was the most prominent code with 129 counts. GOOD LUCK, HOPE IT FIXES IT.

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