Here is the instruction show you guide on how to measure and test fuel return system for Fendt 900 Vario with Deutz engine.
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If the pressure in the return line is too high, the pressure in the dispensing unit also rises. This causes too much fuel to be delivered to the high pressure pumps, which means that the pressure in the rail is above the value set by the engine control unit (A051).
Therefore, if this error occurs, the return pressure must be measured and the target and actual rail pressures must be compared using SERDIA at the same time.
Remove the banjo bolt from the return pipe, screw in banjo bolt with measuring connection 199.110.620.010 and connect a pressure gauge (-1 bar to +1.5 bar)
Target pressure: 0.2-0.5 bar
Connect SERDIA adapter (level 3) to X810 diagnostics socket and launch the program
In the list, find the two values for rail pressure target value and max. rail pressure (see arrows), and compare these two values.If the return pressure is greater than 0.5 bar and the max. rail pressure is greater than the rail pressure target value, the fuel return system must be checked.
First check whether the return lines are kinked. If nothing is observed there, the components must be removed from the return system one after the other. First disconnect the return line from the engine control unit (A051) and connect it directly to the tank, then repeat the measurement. If the pressure is correct now, the problem lies in the cooler duct of the engine control unit. If the pressure is still incorrect, proceed as described above with the next component.
