Outdoor Power Equipment and Small Engines - jd diesel misses and smokes

this is a jd yanamar motor runs good up to about 3/4 throttle then it starts to smoke and miss some I change the air and fuel filters and the fuel lines checked the injecters when it was running running on all 3 cylinders . could it be the injectors are wore out 1800 hrs

I just have to ask, how,, or what,, did you check the injectors for when it was running??? To check them you need to know the pressure they break at & what the spray pattern looks like..& the specs to go with them.. If this is a Mechanical type injection system,, I`d start with a top end valve & injector adjust if it hasn`t been done yet ...Does it have more than one air filter..(a primary & a secondary).. Is this on a farm type tractor with hydraulics,, or an industrial type lawn tractor,, or a stationary engine driving a water pump,, or a generator... Post some model & serial numbers and the application (as JD made lots of applications for this size engine) & the pros will get you dialed in soon.... Roger

I cracked the line at the injector to see if the cylinder was hitting it is a 20hp yanmar

I sold it the problem is fixed

Is the problem fixed,, or it's sold as is & not your problem??? It's too bad,,, If you had told me more than "" It's a 20 hp yanmar"" than I may have been able to help you... You didn't answer any of my questions,, so I have to assume you had it sold before you posted... Sorry,,, Roger