Vacuum Idle Speed Increase
NOTE:
Before testing, check idle speed adjustment.
- With engine at idle, connect vacuum tester (116 589 25 21 00) to straight connection of thermovalve and energize with approx. 13 in. Hg. If idle speed does increase, go to step 2). If idle speed does not increase, check the thermovalves. Make sure that the thermovalve has an open passage. Replace thermovalve, if necessary.
- With engine stopped, check vacuum control unit for leaks. Energize vacuum tester with approx. 13 in. Hg. Vacuum value may drop approx. .30 in. Hg in 1 minute. If vacuum value is OK, go to step 3). If vacuum value is off, check vacuum lines and connections for damage. Replace vacuum control unit, if necessary.NOTE: Replacement of vacuum control unit in injection pump can only be made at a Bosch service station. This procedure requires disassembly of governor and adjustment, only on a Bosch injection pump test bench.
- Check vent line for passage. Pull vacuum line from straight connection of thermovalve and connect with vacuum tester. Operate hand pump, but do not build up a vacuum. If system test is OK, end of test. If test is not OK, blow out vacuum line or replace vent filter. See Fig 1 .