# Occasional rough running JD 6415



## 32-0-0 (May 30, 2017)

Occasionally when starting our JD 6415 it lets out a cloud of dark smoke and runs rough. If you shut it down and then restart it runs smooth as it should, however sometimes it takes few restarts. Have changed both fuel filters and changed the grommets on both ends of the steel line that connects the final filter to the injector but the problem still occasionally occurs. Not sure what to do next…any suggestions would be appreciated.


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## Jerry/MT (Dec 14, 2017)

32-0-0 said:


> Occasionally when starting our JD 6415 it lets out a cloud of dark smoke and runs rough. If you shut it down and then restart it runs smooth as it should, however sometimes it takes few restarts. Have changed both fuel filters and changed the grommets on both ends of the steel line that connects the final filter to the injector but the problem still occasionally occurs. Not sure what to do next…any suggestions would be appreciated.


Does it have a lift pump like the JD6420? Is it running when you turn on the key? Is it pumping?


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## 32-0-0 (May 30, 2017)

Jerry/MT said:


> Does it have a lift pump like the JD6420? Is it running when you turn on the key? Is it pumping?


Yes, it has a lift pump and I can hear it running. Trying to figure out if there’s a pattern to the rough running…after sitting overnight it will start and run as it should,’but if I have to shut it down and start it back up a few hours later, then it will run rough, as if it’s not getting the fuel it needs…sometimes it will run smooth after one restart, sometimes it takes several before it will run smoothly.


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## paoutdoorsman (Apr 23, 2016)

Does it always start quickly, or are there sometimes long crank times before it fires up?


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## 32-0-0 (May 30, 2017)

paoutdoorsman said:


> Does it always start quickly, or are there sometimes long crank times before it fires up?


No long cranks needed regardless of how it runs after it starts…it has always started right up.


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## JRehberg (Oct 11, 2012)

We were chasing a somewhat similar problem on our little 5210. It would crank and run fine but after a while it would run rough and be starved for fuel. This tractor gets used a lot. Changed filters, bled fuel lines, bled injector lines, cleaned fuel cap vent, etc and no fix. We got so desperate we drained the fuel tank and scrubbed the tank out with dish soap and a commode scrubber. We thought perhaps the gunk in the tank was clogging the fuel line after it ran for awhile. Found quite a bit of gunk in the tank even though we use algaecide fairly routinely. Finally, it dawned on us to inspect the fuel primer bulb above filter (the one item we hadn't taken apart). We took the housing apart that the filter screws into and it was nearly clogged shut. We cleaned it thoroughly and no more problems. 

However, a mechanic friend told me to replace the rubber fuel lines; supposedly overtime they begin to weep and will suck in air. He recommended a certain fuel line (the name escapes me) that has an inner lining so the weeping issue won't occur again. This was going to be our next step before we got it running. Might worth taking a look at the line from your tank to the lift pump and filter if they're rubber. He mentioned that if the line is weeping you'll see what look like tiny pin pricks in the rubber fuel line. After the engine runs for a while it will suck minute air bubbles through the pin holes and slowly create fuel starvation issues. Also, it might be worth checking the voltage at your fuel pump; I've been battling low voltage on another piece of equipment lately and it's about to drive me nuts.


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## Farmineer95 (Aug 11, 2014)

Dry fuel. Low sulfur fuel doesn’t have lubricants to allow the pump to operate smoothly. At least this is my experience with a 6400 and what the injection shop told ne. Add a fuel conditioner with lubricity improvers. Might take a tank or more to notice a difference. Try this before sending any components out for rebuilding.


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## Ox76 (Oct 22, 2018)

Lots of lift pumps have a screen built in the intake side. Lots of times they get clogged up with crap from the tank and cause a fuel starvation issue. By turning it on and off and on again sometimes will dislodge just enough crap in a screen like that to let it run again. Just tossing around ideas....hope you get her fixed.


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