Double Throttle Diaphragm Check
- Disconnect vacuum sensing tube from double throttle diaphragm. Apply vacuum of more than 7.8 in. Hg to the double throttle diaphragm.
- Make sure that the No.2 secondary throttle valve is fully closed to its movable range. Check the calibration of the double throttle diaphragm. It should start to open 4.7 in Hg and be fully opened 0-1.8 in Hg. See Fig 1 .