Why does a 2015 Cummins QSB3.3 in a JLG telehandler blow white smoke and lose power under heavy load?

[USVeteran]

My JLG telehandler with a Cummins QSB3.3 runs fine most of the time, but under heavy load, it suddenly blows a big cloud of white smoke and loses power.
Fuel filters were recently changed, and it normally runs clean except during the issue. Could this be an EGR, injector, turbo, or coolant-related problem?

 

[Felipe Rances]

If it's only happening under heavy load, I'd be leaning toward a fuel delivery or injector issue before the turbo. White smoke combined with a power loss can sometimes mean the engine isn't burning fuel completely, so checking injector performance and making sure the fuel system is maintaining pressure under load might be worth a look.