micra k11 blowing fuel pump fuse?

Hi,my son has a 1994 micra 1.0 16v twin cam that has developed a fuel pump fuse fault.
Sometimes it blows new fuse when ignition energised,and sometimes it will start car as normal,when the fuses start to blow again it will even blow 30 amp straight away.
Have had recent problem with the relay situated in drivers foot well that made car run very lumpy,but that resolved when i removed then refitted the original relay.
Could the relay cause the pump to short/blow fuse,any suggestions very welcome.