1976-77 Fox
- With engine idling at normal operating temperature, connect a vacuum gauge between vacuum booster and throttle valve port. Vacuum reading should be 0.2 - 0.3 in. Hg. If vacuum reading is incorrect, check throttle plate for correct position and port for blockage.
- With specified vacuum obtained, move vacuum gauge between vacuum booster and EGR temperature control valve. Vacuum booster is working properly if gauge reads 2-4 in Hg. If not, replace vacuum booster.