Bought a blown 6.4l King Ranch to play around with.. the guy let it sit and got water in the fuel system appears it began to rust. HPFP began eating itself so all fuel stuff is shot (so says typical methods). Pulled the HPFP apart, it is a core anyway, to satisfy my curiosity and get a feel for them, same for the injectors. These things are beutifully simple, but with a high level of precision. HPFP is going in for core so nothing interesting there but I wanted to experiment with the injectors. Got myself an ultrasonic cleaner and started with the nozzles.. not one flowed from all 6 orfices (3 only flowed from 1-2) so started there. They all flow now, so deeper I go. Pulled the top end components, they and the body went in for a bath. Strained (coffee filter) the fluid to get an idea of what lurked inside the injector bodies. Varing degrees of rust and pixy dust, to barely noticable (almost clean). One faily odd thing was 7 and 8 plunger rod/driving spindle (main rod through inj. body) were so cock stiff had to heat the bodies and let weiner shlidin creep in. Even still had to break out the brass punches to persuade them to move. Used some ATF and got them sliding like the rest with no signs of damage/wear. All this and the truck ran, not great obviously but scan tool only had codes for cylinder 5 (hole through piston). Got everthing cleaned and now for some close inspection. The mushroom driving pin and the valve pin guide (also the seating surface of the mushroom) go under the microscope (see pics). Seating surfaces don't look great (not sure what great looks like lol) but this is an experiment so put a couple back together to get flow tested. "Minor" issue is setting the piezo stack nut torque, no matter, set it in the middle of the torque range and see if they flow even close to spec... I appologize for my long windedness, I am going to see where these injectors can be take. Eyeballing the replacement parts direct from china but would still need a shop to tune the injector, or go crazy and get a rig to set the shims myself and then get them flowed. All this just to have some fun in the shop and learn a crap ton about modern diesel injectors. If anyone has had this wind of a hair, interested to hear what you got from it or anyone with the real knowledge (not some i heard or read once bs) on the subject chime in.