Hi, i just recently did a v4sti swap in my 98 club spec evo2. I did this because i myself thought it would be easier having the loom and ecu included which also had the 3plug setup etc... Myself and a good mate did the swap and it was both our first time working on a Subaru. I did the research and also did the same pin swap but also could not for the life of us get the fuel pump to go! After more research i had a bloke tell me that due to in Japan having little to no car theft they did not have alarms or something to that effect...anyway he old me that in Aus they retro fitted imobilisers for insurance purposes because they were being stolen so often insurance companies wouldn't insure owners etc...so he said there was a chip in the key that told the original ecu that it was the right key for that car etc... and turned fuel pump on and the sti ecu didn't recognise this, long story short we earthed the pump with a switch and it fired straight up! I now just run a fuel pump controller with pressure regulator etc... You will have to upgrade fuel pump as my standard rex pump starved when on boost. Did the walbro upgrade and it screams to the limiter! Just thought i would try and help as i know the nightmare i went through lol.