Have Mercedes Questions? Ask a Mechanic for Answers ASAP
Hi, my name is***** tests are you able to perform when the car won't start? Can you test for spark and fuel pressure?
Can you post the last 8 digits of the vin number?
If the relay clicks when you crank the motor you need to confirm that there is 12V to the fuel pump when it won't start. It sounds like you have a fault between the relay and the fuel pump. Test for power at fuse 57 when the car won't start. If you have 12V to the fuse when cranking the motor it tells you that the fuel pump relay is good and there is a fault between the fuse box and the fuel pump or the new pump is defective.
Let me know if you have any questions.