A - Checking fuel consumption in the return lines for all injectors
Remove the upper engine casing. Disconnect hose "2" from the fuel return line. Close the open end of the fuel return line with plug "1". Immerse the fuel return line hose "2" (extend it if necessary) in a measuring container to measure the total fuel consumption in the return line. Start the engine and let it idle for 2 minutes. The nominal value after 2 minutes: from 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 consumption in the fuel return line again. The nominal value after 2 minutes: less than 250 ml. If the nominal value is exceeded, this indicates a malfunction of one of the components (or several) injectors. Check the fuel flow in the return fuel line of each injector.
B - Checking the fuel consumption in the return fuel line of each injector
Note: For each individual injector, the return fuel flow is small. If this value is greater for one injector than for the others, then this injector is presumably faulty.
Before disconnecting all connectors, clean them (e.g. with cleaner "Kaltreiniger"). Dry all cleaned parts. Clamp the return fuel line hose "arrow" using clamps for hoses up to 25 mm -MR7-602 (3094)-. Remove the sound insulation.
Pull the return fuel line fitting out of the nozzle by pulling the "arrow" latches up.
Note: Ensure cleanliness is maintained and prevent contamination from entering the removed return fuel lines and injector connectors.
Firmly place the C6 adapter onto the return fuel line connectors of all 4 injectors. Connect the hoses of the VAS 6684 return fuel line flow meter to the adapter. Start the engine and let it idle for a few minutes.
Caution! Risk of damage to injectors when the return fuel lines are removed. Do not press the gas pedal during the check, the engine must only idle.
The volumes of fuel supplied through the return lines of all 4 injectors, measured on a warm engine at idle, should be practically the same (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.
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