John Deere 4520 surges like governor issues

Hawbuck · Dec 31, 2015

My 4520 surges under any load, sometimes worse than others. It seems like the governor is cutting out and back in seconds. It surges about 100 RPM's

Tx Jim · Jan 1, 2016

:welcome: to TBN
Check for good fuel flow from tank to IP. Check to b sure throttle/governor linkage isn't binding.

beenthere · Jan 1, 2016

And fuel is good (no algae), and filter is clean.

super55 · Jan 1, 2016

It didn't recently run out of fuel or have a filter change did it? Whenever I ever had lunging on the idle it was due to a small amount of air in the system that was eventually purged out after running it at high RPMs for an extended period.

arlen4720 · Jan 1, 2016

What year was it built? Pre 2009? I'm wondering if it's mechanically governed, or the fully electronically controlled engine.

Cidertom · Jan 4, 2016

All the >current< 4520 (not the 1960's version) are common rail fuel systems with electronic control. I've heard of the hydros doing this when the loadmatch isn't working right.

arlen4720 · Jan 4, 2016

Cidertom said:
All the >current< 4520 (not the 1960's version) are common rail fuel systems with electronic control. I've heard of the hydros doing this when the loadmatch isn't working right.

The pre 2009 ones are mechanically governed. Take a look at JD parts and you will see the different fuel systems and where the serial number break was. When eThrottle was introduced on the 4520's and 4720's is when the change was.
Yes I agree with the Loadmatch. I originally thought the OP was talking about idle, but after re reading I see that it is acting up under load.