Toyota 4-Runner 1985 Repair Manual page 150

EC-50 EMISSION CONTROL SYSTEMS (CARB.) - High Altitude Compensation (HAC) System
EC0381
Check Valve
Disconnect
EC0382
EC0383
Sub-diaphragm
Plug
~
~
EC0378
ECl193
(e) Check that the ignition timing advances.
Ignition timing: About 12° BTDC
@
Max. 950 rpm
A03068
2. CHECK THE CHECK VALVE
(a) Disconnect the vacuum hose between the check valve
and vacuum pipe at the vacuum pipe side, and plug
the pipe end.
(b) Check that the ignition timing remains stationary for
more than one minute.
(c) Stop the engine and reconnect the hose to the vacu-
um pipe.
3. CHECK CARBURETOR
(a) Disconnect three hoses from the pipes on top of the
HAC valve.
(b) Blow air into each hose and check that air flows in",
the carburetor.
(c) Reconnect the hoses to the proper locations.
B. AT LOW ALTITUDE
1. CHECK IGNITION TIMING AT IDLE
(a) Warm up the engine.
(b) Disconnect the hose from the distributor subdi-
aphragm, and plug the hose end.
(c) Check the ignition timing.
Ignition timing: 0° BTDC
@
Max. 950 rpm