injection fuel pump seals

[ges]

i have replaced the two o rings on the left and right(looking forwards) not those, replace the seal behind the 3 sided bolt and its still leaking . without a pit is difficult to see exactly where the leak is but there are 2 large seals i havent replaced yet one is about 3 inches and the other is the large gasket-im hoping its not this! the 3 inch one is in front of the block that the 3 sided bolt screws into if you know what i mean. has anyone done this? is is possible do do this with the pump in situ or does the pump need to come out? if i do take the pump out is there anything i need to be careful of? hope one of you has done this and can share a bit of experience would be much apperciated. will the pump come out easily.