Engine Vacuum Pressure
- If vacuum modulator is working properly and downshift linkage is adjusted correctly, all shifts should occur within certain road speed limits. See MERKUR SHIFT SPEEDS TABLE . If shifts do not occur at proper points or slipping occurs during shifts, check engine vacuum, vacuum supply, and vacuum unit for possible cause of problem.
- Connect tachometer to engine. Connect vacuum gauge to manifold vacuum line, using "T" fitting at modulator hookup. Attach pressure gauge to control pressure outlet on transmission case. See Fig 1
.CAUTION: Pressure gauge affects quality of transmission shifting. When gauge is installed in transmission port, DO NOT accelerate or decelerate rapidly as transmission failure could occur.
- Apply parking brake. Start engine. On vehicle equipped with vacuum brake release, apply service brakes. Parking brake automatically releases when transmission is moved to "D".
- Adjust engine idle speed to correct RPM. If engine idle cannot be brought within limits, check throttle and downshift linkages for binding. Check for vacuum leaks in hoses and tubes if linkage is correctly in place. Check vacuum units such as power brake booster for leaks.