Carburetor Maintenance
The carburetor requires virtually no maintenance in operation. If necessary, the carbon monoxide content can be checked and adjusted (SO) in exhaust gases. Periodically check the tightness of the air hose connections. After washing the engine, the carburetor must be treated with an anti-corrosion compound such as WD40 or Um-Spray Termal.
To clean the carburetor after checking the condition of the engine, ignition system and system «Ecotronic» remove the carburetor and clean its outer surfaces. Cast and steel parts are cleaned by immersing the carburetor in a bath filled with a special detergent composition, after removing all electrical elements and plastic parts from the carburetor (including inlet fuel filter). After drying, wash all parts of the carburetor with white spirit and blow out the holes and internal channels with compressed air. When assembling the carburetor, replace worn parts (make sure there is no backlash in the throttle valve axes) and ensure free movement of all moving parts
Check the tightness of the connection between the carburetor and the intake manifold. The tightening torque of the carburetor mounting bolts should be in the range of 8-10 Nm.
Checking and adjusting the carburetor
To check the controller, wires and electrical components of the system «Ecotronic», mounted on a carburetor, it is best to use the Bosch SIS Universal Tester. If it is not there, then a tester can be used for these purposes (in ohmmeter and voltmeter modes).
Engine idle check
Before checking idle check:
- adjustment of gaps in the gas distribution mechanism and compression in the engine cylinders;
- setting the ignition timing and the serviceability of the spark plugs;
- serviceability of electrical elements, wires and their connections;
- tightness of the intake tract;
- the cleanliness of the air filter element;
- serviceability of the intake air heating system;
- adjustment of the carburetor control drive.
In addition, it is necessary to disconnect the crankcase exhaust hose from the carburetor to the throttle device, turn off the electricity consumers and warm up the engine (oil temperature around 70°C), then check the idle speed of the engine, which should be within 800-900 rpm (before MY 1985) or 750-900 rpm (from model year 1985).
Engine idling is controlled by the controller and is not adjustable in operation (in the design of the carburetor there is no adjusting screw for the amount of idle mixture). However, if necessary, you can increase the idle speed by about 100 rpm by connecting the two wires (see photo) under the instrument panel on the right.
Check the CO content in the exhaust gases, which should be no more than 1.5% (before MY 1985) or within 0.3-0.7% (from model year 1985).
If the value obtained does not fit within the specified limits, use the mixture quality adjusting screw to achieve the proper CO content in the exhaust gases, after removing the screw plug.
After adjustment, install a new plug in the hole for the mixture adjustment screw.
Checking the intake air temperature sensor
Disconnect the sensor connector and check its resistance directly on the plugs, which at an intake manifold wall temperature of 20°C should be within 2-3 kOhm. at a temperature of 80°C - within 280-360 Ohm.
If abnormal, replace the intake air temperature sensor.