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FIXITMAN, Master Technician
Category: Mercedes
Satisfied Customers: 17284
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Im ***** ***** I was driving my 07 S550 down the road when

Customer Question

Customer: Im ***** ***** I was driving my 07 S550 down the road when it turned off, I pull over and car would not start.
JA: Thanks. Can you give me any more details about your issue?
Customer: When I tired turn it on it cranks but doesn't turn on, I check the rear battery voltage and it sits around 11.6-12.0 and the start battery at 12.0 and when I crank the car to start it the starter battery drops to 10.9 and the rear around 11.5.
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Submitted: 1 year ago.
Category: Mercedes
Expert:  FIXITMAN replied 1 year ago.

Hello, my name is Bobby. Thank you for the question. If the engine is cranking over and the vehicle is just not starting then it may be a failed fuel pump or possibly a crank sensor problem. If it is not cranking it can be an electrical issue as it sounds like you have enough voltage for it to crank over. Do you have a scan tool to see if there are any codes in the computer?

Customer: replied 1 year ago.
no I don't have a scan tool. How can I test the bad fuel pump
Expert:  FIXITMAN replied 1 year ago.

If you have a fuel pressure tester you can test the pressure at the fuel line under the hood. Or if you listen closely to the fuel tank see if you can hear any noise from the pump when the key is first turned on. If not then the pump may be bad.

Customer: replied 1 year ago.
where can I find the pump?
Expert:  FIXITMAN replied 1 year ago.

It is located inside of the fuel tank. The fuel tank is located underneath the car. You should have an access panel under the rear seat to more easily get to it.