John Deere X390 Engine Surging

[clubproguy3]

My 2016 JD X390 54 in. Deck with 443 hours is surging, pretty bad. More so when I idle up. It'll run decent at very low idle while im not moving. I've put some "mechanic in a bottle" in it. I've switched over to premium gas, hoping this would help it run smoother but no luck. I'm guessing carburetor? I just had it serviced thinking it was just a clogged filter/fuel filter of some sort but got it back and now it's doing it again.

Will run fine for maybe 20/30 minutes some times and other times, can't even make it out of the garage. Had to put a new PTO Clutch on it as well so I'm north of 1K in repairs on this thing and not really wanting to put anymore into it.

Any ideas/trips/tricks?

 

[EFSM]

It sounds like it could be a carburetor problem, but you should also check fuel flow through the pump. Take the hose off the pressure side of the pump and it should shoot out nicely when you crank/run it. If it only dribbles out part of an inch, it could be the pickup fuel line is clogged. Some of those John Deere's don't have a screen on the end of the pickup fuel line. If fuel flow is adequate, it's probably dirt in the carburetor. You could try removing the solenoid on the bottom and draining the bowl to see if it has a "floater" in it that's giving you trouble. It is probably a single barrel carburetor; if it is a twin barrel, make sure both idle circuit welch plugs are still there (on the top of the carburetor).

 

[Coupe]

If you take the carby off to clean it make sure you check and clean low idle jet. Quite often
if it gets blocked or semi blocked they can do some strange things at idle.
Also a govenor spring that may have got stretched a bit can make them do some funny things at idle.
Should only think it would be something minor but I would got straight at the carby and give it a really
good clean and eliminate any problems that maybe there. And then go from there. With chainsaws I allways start
at the tank check tank filter and them take that little filter off and plug my mityvac preasure tester in and pump
2 or 3 pds in and by doing that you can test for a hole in fuel hose and also test that needle valve in not leaking.