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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53904
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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My 2006 Mercedes ML 500 Cranks but won't start. It has a new

Customer Question

My 2006 Mercedes ML 500 Cranks but won't start. It has a new crank sensor, fuel pump, fuel filter, fuel pump relay and MAS. Is starts and runs great for a few days and then it just won't start again
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 1 year ago.

Hi, my name is***** tests are you able to perform when the car won't start? Can you test for spark and fuel pressure?

Customer: replied 1 year ago.
It has no fuel pressure. The power is getting to the fuel pump relay and the relay is clicking. I checked all the wire connections and made sure they had electrical contact and it ran fine for a month and now won't start again.
Expert:  Marty replied 1 year ago.

Can you post the last 8 digits of the vin number?

Customer: replied 1 year ago.
6A002541 Is the last 8 of the vin
Expert:  Marty replied 1 year ago.

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.