injection pump failures?

[dieselpower]

hey,
i've heard injection pumps can fail from running conaminated fuel, getting water into them, getting a little dirt into them, and they just fail by normal waer and tear.

my question is, what parts actually get wrecked that cause it to stop working. like if i have a high milage pump or am going to convert to SVO/WVO are there certain parts in it i could change to make sure it lasts longer?

any info is appreciated

Mark

[QuickTD]

The most common high mileage failures in the injection pumps are the reciprocating parts in the head. The camplate and rollers begin to spall and flake after a large number of miles. It seems to depend on the particular camplate profile. 1.9TD's and TDI's have a fairly aggressive profile and tend to fail more often than 1.6's. Once metal starts to flake off the rollers it gets into the head/plunger and tears them up. The only other part that wears out with high miles is the vane type transfer pump and the bushings on the input shaft. There is no way to predict the life of any of these components.  

 Dirt usually affects the close tolerance parts like the head, plunger and control ring first. It can scratch the surfaces and cause internal leaks. The high pressure plunger is sealed only by a close mechanical fit, surface imperfections can cause problems. Damage to the high pressure section of the pump causes hard starting when the engine is hot and the viscosity of the fuel is low.

I have seen a failure of the plunger springs in a high mile pump. I've also seen the advance piston seize from water sitting in the bottom of the pump, though these are not common failures.