just thought i'd share my Injection Pump (IP) rebuild experience (on our jdm land cruiser) from Giles Gallie at http://www.performancediesel.ca/about.htm. I know there are mostly gassers here but i do know there are some diesel owners around.
the 1991 HDJ81 has been due for an IP (rotary pump) rebuild for a while now. I can only assume that it hasn't been touched ever as I bought the 80 in 2006 with less than 50K kms on it (one owner in japan before the dealer brought it here) and i've put in about 120K kms since. I previously heard about Giles from other cruiser guys and he has since done some minor IP work on an older cruiser i had (bj 60 with inline pump) and the service was awesome. I've heard nothing but great things and there aren't too many IP specialists around so i went ahead and dropped the rig off at his Shop. he was worked on IP's for over 20 years and he is well known in the diesel tuning world (i.e. tdi jetta guys).
He hasn't done much work on toyotas so i was a little leary but he assured me that taking the IP out (and after he saw how simple the 1hdt motor looked/timing cover removal, etc) would be pretty straight forward. I was fine with him taking his time as his shop is quite busy with a regular stream of IP's waiting for a rebuild (mostly shipped in or dropped off).
by the end of the week, the IP was done and the rig was ready for pickup! Now, i know nothing about IP's except the fact that they are the heart of a diesel engine and there are a tonne of bits and crucial timing of moving parts that need to happen for the engine to run smoothly and efficiently. I can only comment on the experience after i checked the shop out and learned about the process. and at the end of the day, it boils down to how the truck feels performance wise and mileage.
the process is basically, remove the IP, take it appart, wash the pieces thoroughly, replace the seals, rebuild, bench test/calibrate(? this is where the magic happens) and reinstall.

here's a shot of the 3 stage cleaning process they have

(Not my pump, but a smiliar one to mine all apart/cleaned and ready for reassemble..)

the original seals, very brittle from age (23 yrs..), and the source of the leaks..

one main seal that was twisted (either it wasn't installed perfectly from the factory, or maybe the IP did get serviced in japan once..?)

and here's the IP test bench where all the fine tuning happens (looks very complicated!)