Deere 6420 rough running

[Jeff Thomas]

I have a 6420 4wd that runs fine most of time. However, every once in a while it runs rough sounding as though air is in line or it has bad fuel. If you turn the tractor off then on again its solved the problems mist of the time. Changed the filters and checked for air but still does it every once in awhile. I called a John Deere mechanic and he said it could have something to do with a sensor in the fuel injector pump. They are 3000 dollars. Anybody have similar problems?

 

[jenkinsph]

Sometimes air leaks can be hard to find and intermittent too.

New fuel pumps are expensive but doubt this is your problem at least it should not be necessary to replace it. Most people try to find a good reputable injector pump shop and have the pump rebuilt and adjusted to specs. Even the typical Deere dealer sends the pumps out to be repaired just as starter and generators are sent to their respective shops.


I would go over all the lines with a fine tooth comb, clean everything up well so you can see if it leaks fuel. I would also check the return lines to make sure none of them are stopped up. Tighten all the tubing lines with tubing wrenches to specs. I had a fuel siphon pickup tube (in the tank) in one of my tractors develop a small crack in it, it about drove me crazy sometimes working ok and other times not. Recognize that from the 1st stage fuel transfer pump back to the tank the fuel line is at a slight vaccum so if any thing is loose or pin holed it can draw in air ( air entrainment). If nothing seems to work after checking the above I have spliced in a piece of fuel grade clear hose at the main transfer pump outlet to see if any air is being entrained. Should also add that the transfer pump diaphram can have a pinhole in it too. Check the tubing when you are having the rough running.

Next and only after trying the above I would remove the injector pump and send it in for service. They do need to be rebuilt occasionally but rarely need to be replaced with new.

Keep us posted on your endeavor.

 

[JESSE1]

The fuel line from the tank to the filter has a bad habit of going bad after a number of years. Your tractor is still pretty new but I'd recommend changing out the fuel line. My 6400 started getting air in the filter any time it sat for a day. The fuel line was seeping just enough for air to get in it. Changed it out and no more problems.

 

[FMcCool]

Yes, about exact same as you. I have '03 JD 6320 doing the same and dealer does not seem to know how to solve. Made similar changes, fuel filter, check valve, and fuel shut-off solenoid all replaced to no avail. Going to contact someone at JD Hqs. at this point.

 

[FMcCool]

Follow-up note; I expect you already checked fuel injectors by backing off on individual lines with engine running. Resultant loss of power would show that the injection pump is good. Also would assume you checked that primary and secondary air-filters are good. Do you have any check lights showing when problem arises? I do not.

 

[sixdogs]

The fuel line from the tank to the filter has a bad habit of going bad after a number of years. Your tractor is still pretty new but I'd recommend changing out the fuel line. My 6400 started getting air in the filter any time it sat for a day. The fuel line was seeping just enough for air to get in it. Changed it out and no more problems.

Bingo. I have a six? year old 5520 with same(?) engine--and spent agonizing hours trying to figure out the same problem.
It was a rotted fuel line that I didn't realize had a slow leak from rubber-rot cracking.
Rather than the gamble of another line at Deere I got the correct line at NAPA and hope the quality is better.
Mine is an open station tractor and the line was not a straight shot and very difficult to change. Maybe three hours?
If the fuel line is OK, I like the idea of calling JD at the home office.

 

[Jeff Thomas]

Yes, about exact same as you. I have '03 JD 6320 doing the same and dealer does not seem to know how to solve. Made similar changes, fuel filter, check valve, and fuel shut-off solenoid all replaced to no avail. Going to contact someone at JD Hqs. at this point.

Let mrs know what you find out

 

[bchambley]

I have 3 tractor with the same engine. It seems that around 2,000 to 2,500 hours the injector pumps start to give problems. I have had to rebuild all three. The cost was around $1,000. All tractors have done exactly as you described, and the rebuild solved the problem.

 

[Jeff Thomas]

I have 3 tractor with the same engine. It seems that around 2,000 to 2,500 hours the injector pumps start to give problems. I have had to rebuild all three. The cost was around $1,000. All tractors have done exactly as you described, and the rebuild solved the problem.

Where have you had them rebuilt. Also is there any issue reinstalling them.
Thanks

 

[REGRACO]

WERE YOUR PUMPS ELECTRIC STYLE ?