A - Checking the fuel consumption in the return lines for all injectors
Remove the top engine cover. Detach hose -2- from fuel return line. Close the open end of the fuel return line with plug -1-. Fuel return hose -2- (lengthen if necessary) immerse in a measuring container to measure the total fuel consumption in the return line. Start the engine and let it idle for 2 minutes. Nominal value after 2 minutes: 0 ml to 50 ml. If the nominal value is reached, increase the speed to 2000-2500 rpm for 2 minutes and check the fuel flow in the fuel return line again. Nominal value after 2 minutes: less than 250 ml. If the nominal value is exceeded, then this indicates a malfunction of one (or more) nozzles. Check the fuel flow in the fuel return line of each injector.
B - Checking the fuel flow in the return fuel line of each nozzle
Note: The fuel return flow is small for each individual injector. If this value is greater for one of the injectors than for the others, then this injector is presumably faulty.
Before disconnecting all connectors, clean them (e.g. cleaner «Kaltreiniger»). Dry all cleaned parts. Clamp off fuel return hose -arrow- with hose clamps up to 25 mm -MP7-602 (3094) -. Remove soundproofing.
Pull the fuel return connector out of the injector by pulling the catches upwards -arrows-.
Note: Maintain cleanliness and ensure that removed fuel return lines and injector connectors do not get contaminated.
Firmly put adapter C6 on the connectors of the fuel return lines of all 4 injectors. Connect hoses of fuel return flow meter -VAS 6684- to adapter. Start the engine and let it idle for a few minutes.
Carefully! Risk of damage to the injectors when the fuel return lines are removed. During the test, do not press the gas pedal, the engine should only be idling.
The volumes of fuel supplied through the return lines of all 4 injectors, measured on a warm engine at idle, should practically not differ (example -1-). If the fuel consumption in the return line of one of the injectors is clearly higher than the others (example -2-), then it needs to be replaced.
