JD 4520 compact tractor [2004] engine surges

[Crankygranke]

Engine surges like fuel starving momentarily then comes back and repeats. this happens at all speeds. any time under load is worse. I've replace filters, fuel and trans. It's a power reverser. replaced fuel lines, cleaned fuel tank, replaced the transfer pump, air filters. 1800 hrs on tractor. Starts fine, no smoke and does not miss. Any help will be appreciated. thanks

 

[thepumpguysc]

There is a spring on the throttle shaft that break and/or get worn..
Make sure there is a solid connection between the pump throttle & the linkage, no slop.
If u could provide some pump #'s off the tag, that would be most helpful.. JD put several diff. pumps on that tractor.

 

[MBBuilders]

Just had the same problem with my JD 5320, it had some sort of sludge in the tank (looked like half dried silicone) it would suck it into the line and would starve motor of fuel

 

[Crankygranke]

each injector has it's own pump. all in the head. no external pump. linkage is fine

 

[Crankygranke]

i cleaned the tank and the screen at the out flow. a little dirty but all clean now.