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Matt
Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 20789
Experience:  BEng hons Mech engineering, in auto industry 22 years
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My Mercedes A160 (2009) lost power last week. I fuelled up

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My Mercedes A160 (2009) lost power last week. I fuelled up at a Supermarket in the morning - drove about 40 miles to my Mothers then 20 miles into the journey on the way back I went from 60 to zero in about 4 seconds. It would not restart. The car sat for about 4 hours in between journeys. Mileage is currently 39000. Managed to restart after about 20 minutes but temperature going haywire all the way home for the last 20 miles. Took to garage who said water in fuel - put in fuel cleaner and cleaned fuel pipes. Attempted to drive home (£155 lighter!) and 3 miles up the road the same happened again. from 60 to zero in 4 seconds. Garage now say it is fuel pump. This is my 2nd Mercedes A class and never had a problem before. Is this a common fault in this model for 2009? We keep the car well and ensure serviced regularly etc. Thank you
Submitted: 1 year ago.
Category: Mercedes
Expert:  Matt replied 1 year ago.
Hello

This sounds like an electrical actuator or sensor at fault .Usually when you can cycle the ignition key on / off and then restart the engine and the fault is gone temporarily this indicates that this is an electrical component causing this issue.

This could be a wiring issue as things tend to expand when hot and its possible a poor or partial electrical connection is being pushed apart on one of the major sensors so check the connection plug and wiring to the following;
Airflow meter
Crank position sensor
Cam position sensor
O2 sensor
Throttle position sensor

unplug each in turn and use some switch / contact cleaner spray on the pins to ensure its all grease / dirt free

Also worth checking the connections to the fuel pump for the same reason - unplug each in turn and give them a good squirt of switch / contact cleaner - Not WD40

and also unplug and inspect the main power relays and fuses for signs of overheating or corroded terminals - so the ones for the ECU and the fuel pump

And also unplug the wiring loom connections in the engine bay one at time and inspect for corroded or recessed pins.
Also replace the spark plugs if any of them fail this checklist:

http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp

Also its worth checking that the electric pump that feeds the injectors is working correctly, it should run for a few seconds then switch off when you first turn the ignition on. If the connections to this are corroded or damaged then the pump could stop at any time. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse, ideally measure the voltage at the pump and check its getting 12V
Customer: replied 1 year ago.

Many thanks for this. We will ask the garage to have a look at what you have suggested but are you ruling out the fuel pump all together?

Garage seem to be going to fit new pump tomorrow.

Thank you

Expert:  Matt replied 1 year ago.
Hello

if you see my 1st reply I said the fuel pump is a possibility so replacing it stands a good chance of solving the issue
Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 20789
Experience: BEng hons Mech engineering, in auto industry 22 years
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