cardiagn.com (b) Check the flow control valve for leakage. Close one of the holes and apply compressed air 392 to 490 kPa (4 to 5 kgf/cm 2 , 57 to 71 psi) into the opposite side hole, and confirm that air does not come out from the end holes. If it is necessary, replace a new vane pump assembly. 4. INSPECT SPRING (a) Using a vernier caliper, measure the free length of the spring. Minimum free length: 31.3 mm (1.2323 in.) If the length is less than the minimum, replace a new vane pump assembly.