I just swapped my injection pump with one I bought at the junkyard for a song. The original one didn't seem to run well, hard starting and the idle adjusting know would not turn. I think someone adjusted it with the engine running.
One of the pipe unions was rusted and plenty of PBlaster eventually freed it. The cold start valve pipe needs to he the rust removed, the idle air pipe needs cleaning, the fuel supply hose was brittle and broke. I need to replace the hose portion.
BTW, I didn't time the injection pump and just installed it. The 2 plunger pump feeds 3 cyls each, so why bother.
OP, make sure the area is clean and don't let any dirt get into the pump. Read the 'Linkage Tour' post at the top of this forum.