John Deere comonrail engine trouble (T550)

Hi all,

I've been having engine trouble with this combine since i got it second hand (wonder why it was sold... ). It's a 2010 John Deere T550 with a 6068HZ482-DD21359 engine. The problems were intermitent in the beginning but now got more constant and disabling. It's throwing the ECU 1347.07 code - fuel rail pressure mismatch. A lot has been done to try to overcome this problem with little success. In the past year i've changed: rail pressure sensor, fitted reman injectors from JD, refurbished the electrical harness (some wires insulation were stuck together, i've replaced that section with heat resistant wires and new connectors, all connections soldered), 2 x suction control valves.


This video is from yesterday morning, in the yard,when while checking something around it, the engine started going really bad, the RPM would oscilate from 2550 to 2080. I turned it off and on and couldn't reproduce that again, but this whole week it was running badly, throwing that code, smoking and guttless. After this video, i started harvesting and went ok (as in really good) for one length of field, then started going rough again. I had a mechanic come and change the SCV. After that it worked flawlessly until today afternoon when it threw that same code, started smoking and being guttless again.

This is what i really don't understand: The symptoms in the video would sugest a faulty SCV. It was replaced and worked perfectly for about 15 hours, then started doing it again. Out of curiosity i took apart an old SCV and it's just a coil, no other electrical components, it measured 2.5 Ohms either way i put the probes and the copper wire looked perfectly fine, no sign of overheating, so i find it hard to beleive that the electrical part of the SCV is broken. If it's the mechanical part that's broken, why? why would it work fine on ocasion?

The pressure limiter valve was not changed recently but if that's faulty why would it ocasionaly work fine? The ECU was also changed at one point and didn't cure it so put the old one back.

@NZ Tech , @Tractortech , anybody had this kind of problem?

Inconveniently, the combine ran fine when the jd guy came and hooked up his laptop. He changed the SCV because i showed him the video and described how it was acting.
If i fit a clear hose to the rail pressure limiter how can i block the pipe that goes from it to the return?

Deerefarmer said:

If you do a google search of your fault code you will find lots of threads and solutions across the www.
Transfer pump working....check for debris plugging suction port in fuel tank?

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I did search, there's another code if there's not enough pressure on the LP side. Tank has been removed and washed in the last years, transfer pump has been replaced as well. Still doesnt explain why it worked ok after changing the SCV, but only for a few hours

lexion780tt said:

Sounds like the it may actually be the hight pressure pump has actually failed gave you a tractor you could swap it with? If you pull the plug off scv what's it like then will go max rail pressure and should blow limiting valve off on rail?

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I thought about the HP pump too, but how come it worked so good after changing the SCV, then in the middle of the next day it started misbehaving again?
As i said, ive had these kind of problems since i got it but less frequently. In the beginnibg it would throw this code once in a while, i would cycle power and then it would work for hours/all day without any issue. Last year it started to be more frequent hence my decision to replace the injectors this spring, as advised by JD but with no success. Now i've changed the SCV and i saw a huge improvement over the last days, only it didn't last for more than about 15 engine hours.

How do these HP pumps fail when they do?

Todays update: starte it, turned on the separaor and feeder (no header attached), max rev and right away it started oscillating the revs 2550 - 2080, kept doing it even after shutting down the separator. Then i wanted to catch it on video so turned it off, started filming and this is the video:

It didn't do it!

Cycled power again and started filming when it went wrong again, but this time the rpm stabilised itself after 2 or 3 swings:

lexion780tt said:

Would suspect the wiring isn't good to the scv if it goes open circuit will run awfull as go to max rail pressure and relief valve on rial will open.

Clean up the terminals In the plug and chech wiring to ecu if all OK id take hp pump off and get it tested

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Thought about that and i replaced the wires from the ecu to the SCV, good quality heat resistant cable, 1.5mm, teisted, soldered new connector at the SCV

Flat 10 said:

Has it brand new filters? I don’t think SCV is the problem. What happens if you unplug the SCV?

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No, it does not have new filters but used to get a different code, on the low pressure side, there-s a pressure sensor on the second filter housing. If i unplug the scv it will definitely wreck the rail pressure relief valve

lexion780tt said:

When you changed the injectors did you change the stack tubes to the injectors.

What fault codes are you getting now?

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What do you mean by stack tubes? They also changed the 6 pipes from the rail to the engine

I get 1347.07 whenever it begins misbehaving