8.13. Control system of a carburetor pneumatic valve

Check of operability of the control unit 25.3761

Fig. 8-45. Scheme of a control system of a carburetor pneumatic valve: 1 — the microswitch in the carburetor; 2 — a pneumatic valve; 3 — the assembly block; 4 — the ignition relay; 5 — the ignition switch; 6 — the control unit of a pneumatic valve; 7 — the ignition coil; And — to a conclusion "30" generators; B — an order of conditional numbering of plugs in the control unit

The serviceable control unit 25.3761 has to disconnect a pneumatic valve of 2 (fig. 8-45) with a frequency of rotation of a bent shaft of the engine more than 1600 min.-1 and again include when turns fall up to 1200 min.-1.
Before check of operability of the block it is necessary to be convinced of correctness of connection of a plait of wires of the car to the control unit (see a type of "B" on the control unit socket).
Operability of the control unit is checked by means of a tachometer and the voltmeter (with limits of measurement of 0-15 V) in the following order:
— disconnect wires from the microswitch installed on the carburetor;

Fig. 8-46. Scheme of check of the control unit of a pneumatic valve: 1 — the control unit;
2 — transitional I will corrode with the voltmeter; And — a plait of wires of the car

— connect to the control unit 1 (fig. 8-46) the voltmeter by means of the special transitional socket 2;
— start the engine and, gradually increasing rotation frequency, you monitor indications of the voltmeter: after start of the engine the voltmeter has to show voltage not less than 10 V, and at the time of shutdown of a pneumatic valve — spasmodic undervoltage up to the size no more than 1,5 V;
— after shutdown of a pneumatic valve gradually reduce rotation frequency to inclusion of a pneumatic valve: the voltmeter has to show at the same time spasmodic increase in tension not less, than up to 10 Century.
It is allowed to check the block without voltmeter on characteristic knock of the valve at shutdown and inclusion.
Check of the control unit of the electromagnetic valve
If the engine has the carburetor 21053-1107010, then instead of the control unit 25.3761 of a pneumatic valve the control unit of 501.3761 type of the electromagnetic valve of the carburetor is installed.
The control unit 501.3761 has to switch-off the valve with a frequency of rotation of a bent shaft higher than 1900 min.-1 and include at 1700 min.-1. Addresses of output plugs of the control unit are specified in table 8-9.


Operability of the control unit is checked by means of the transitional socket with the voltmeter in the following order:
— disconnect a wire from the trailer switch of the carburetor and connect a tip of this wire to weight;
— connect to the control unit the voltmeter by means of the transitional socket;
— start the engine and, gradually increasing rotation frequency, you monitor indications of the voltmeter: after start of the engine the voltmeter has to show voltage not less than 10 V, and at the time of shutdown of the valve — spasmodic undervoltage up to the size no more than 0,5 V;
— after shutdown of the valve gradually reduce rotation frequency to turning on of the valve: the voltmeter has to show at the same time spasmodic increase in tension not less, than to 10 V;
— establish the frequency of rotation of a bent shaft within 2200–2300 min.-1, disconnect a tip of the wire going to the trailer switch of the carburetor from weight and then again connect it to weight. At a wire detachment from weight the valve has to turn on, and at connection with weight — to be disconnected.
It is allowed to check the block without voltmeter on characteristic knock of the valve at shutdown and inclusion.