Checking the control unit
Serviceable block 5 (pic. 7-41) control should turn off valve 6 when the crankshaft speed increases to 2100 min-1 and turn on the valve when the speed drops to 1900 min-1, if the carburetor limit switch is closed to «mass».
Pic. 7-41. Connection diagram of the carburetor solenoid valve control system:
1 - ignition switch; 2 - ignition relay; 3 - ignition coil; 4 - control unit; 5 - solenoid valve; 6 - carburetor limit switch.
Before checking the operation of the unit, make sure that the wires are connected to it correctly.
The operation of the control unit is checked using a voltmeter (with measurement limits 0-15 V) in the following order:
- disconnect the green wire from the carburetor limit switch and connect the tip of this wire to «weight»;
- connect a voltmeter to the control unit using a special connector 2 (pic. 7-42);
- start the engine and, gradually increasing the speed, monitor the voltmeter readings: after starting the engine, the voltmeter should show a voltage of at least 10 V, and at the moment the valve is turned off, an abrupt decrease in voltage to a value of no more than 0.5 V;
- after turning off the valve, gradually reduce the speed until the valve is turned on: the voltmeter should show an abrupt increase in voltage to at least 10 V;
- set the crankshaft speed within 2200-2300 min-1, disconnect from «masses» end of the wire going to the carburetor limit switch, and then reconnect it to «weight»; when disconnecting the wire from «masses» the valve must turn on, and when connected to «weight» - turn off.
Pic. 7-42. Control unit test scheme:
1 - control unit; 2 - adapter with a voltmeter;
A - to the car wiring harness.
Note. It is allowed to check the unit without a voltmeter by the characteristic knock of the valve when turning it off and on.