31 should be the earth
30 should be pump feed 12v
87 is the output from the realy down to the pump
15 and 1 are the trigers from the coil and ignition module

so just check you have an earth at 31 (continuity to car body)
you have already proved yourself 30 and 87 are ok by linking them out,
15 and 1 should be live (12v)when attempting to start engine,

that should find the problem or help narrow it down a fair bit.