At each maintenance, the operation of the carburetor solenoid valve control system must be checked (forced idle economizer).
Before checking, make sure that the wires are connected to the control unit correctly. To check, you need a tachometer that controls the speed of the crankshaft, and a voltmeter with measurement limits of 0.15 V. The check is performed 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 2 (pic. 134) using a special connector.
Start the engine and, gradually increasing the crankshaft 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 not more than 0.5 V. After turning off the valve, gradually reduce the speed until the valve is turned on. At the same time, the voltmeter should show an abrupt increase in voltage of at least 10 V. Check on the tachometer whether the valve actuation frequencies correspond to the frequencies indicated on the control unit.
Set the crankshaft speed within 2200... 2300 rpm, disconnect from «masses» tip 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.
It is allowed to check the control unit without a voltmeter by the characteristic knock of the valve when turning it off and on, respectively, during a smooth increase and decrease in the engine speed.