fuses blow because of a short circuit ie somewhere a wire is touching metal where it should not efectivly shortening the wire.my guess would be somwhere in the harness that moves when the engine rocks on the starter.rearrange the wireing harness looking out for a small  clean spot  that might indicate a short.having someone crank while u watch the engine move might show u whts touching .all it takes is 1 stand of wire to touch.look for wear marks,insulate any breaks
                 caine
                
 June 2008