Increased idle speed
1. Attach a tachometer to the engine (see chapter "Engine adjustment").
2. Turn the high idle cam (Ah, fig. F:12) so that the adjusting screw (B, fig. F:12) was at the highest level of the fist.
3. Start the engine without touching the accelerator pedal and note the high idle speed.
4. If the value obtained is outside the limits specified in the section "Technical data", remove the protective cap and adjust the speed with the adjusting screw (B, fig. F:12).
Air damper starting gap
1. Remove the air damper cover with water box without disconnecting the electric heater wire or cooling system hoses.
2. Open the throttle and turn the high idle cam (Ah, fig. F:12) so that the adjusting screw (B, fig. F:12) stopped at the highest step of the cam.
3. While pressing the air damper start gap adjustment screw with a screwdriver, push the air damper rod towards the vacuum unloader until it stops (pic. F:13).
4. Check the gap between the edge of the air damper and the wall of the carburetor diffuser using a drill of the appropriate size (see section "Technical data").
5. If necessary, adjust the clearance by turning the adjusting screw (pic. F:13).
6. Replace the choke actuator cover; The mark on the cover must be aligned with the mark on the body.
Unloader
Check the operation of the vacuum unloader as follows.
Remove the air filter and start the engine at idle. By manually closing the air damper plate, check the operation of the unloader: if the air damper closes easily to a gap of 4 mm and then resistance is felt, the unloader is working properly. If the air damper closes completely without resistance, the unloader diaphragm is torn or there is a leak (air leak) in a vacuum system.
Intake manifold heater
The heater integrated in the intake manifold can be checked as follows:
1. Disconnect the heater connector next to the carburetor
2 Measure the voltage across the disconnected heater wires with a voltmeter. With a cold engine and the ignition on, the voltage should be approximately 11.5 V. If the voltage is not as specified, check the thermal switch (see below).
3. Measure the resistance between the heater wire and "weight" (pic. F:14). The resistance should be 0.25-0.50 ohm. If the resistance is different, replace the heater.
Thermal switch
A thermal switch box built into the engine cooling system controls the power supply to the air damper actuator heater and intake manifold heater based on coolant temperature. The unit includes two thermal switches: the red thermal switch controls the automatic air damper actuator heater, and the transparent one controls the intake manifold heater.
Check the operation of the thermal switches with a test lamp. Disconnect the electrical wires and connect the lamp between the wire connector and the thermal switch. At the cold engine and the included ignition the control lamp should burn, otherwise replace the thermoswitch. If the lamp lights up, remove the thermal switch and hang it in a container of water, leaving it connected to the test lamp circuit. Heat the water, watching the temperature - the control lamp should go out at a temperature of 30-40°C (red thermal switch) or 50-55°C (transparent thermal switch). If not, replace the thermal switch.
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