KOMATSU PC 130 DASH 7 PRESSURE PROBLEMS

AS SOON AS I FIRE UP I'VE GOT HIGH PRESSURE - 300 BAR .THE PRESSURE IS THERE WITH THE SAFETY LEVER ON OR OFF. I'VE CHECKED THE HAMMER VALVE OK THE DECEL WORKS WHEN I PULLED THE LS PIPE OFF AT THE PUMP THE PRESSURE DROPPED TO 140 BAR ALL SERVICES WORK OK. DO YOU THINK THERE IS SOMETHING STICKING IN THE PUMP
I'LL BE GLAD OF YOUR VIEWS TIA red diesel