cherishzm

Hello.

I have a 2004 CLK 500 with 50k miles that died while driving on a highway yesterday afternoon. I drove it for a couple hours without any issues earlier then suddenly, it won't respond to gas pedal and and died eventually on a side of the road. I tried to start it and it turned over, but didn't start even when the engine cooled down. Fuel level is about 1/2 and I never had an issue with starting the car in the past (owned it for a year).

I had it towed home and found the Crankshaft Position Sensor is a common problem and symptoms are similar. With the information on this forum, I was able to replace it just about an hour ago and hoped it'd fix the issue, but it does the same - it turns over but won't start. By the way, I noticed the old CPS was kind of wet when I pulled it out.

Now, what should be the next thing to check??

Any help would be appreciated!

gaazmon

Bad CPS wouldn't cause the car to shut off mid-drive, but probably was a good idea to replace anyway since they all go bad eventually. Were the electronics still functioning normally just no power to the pedal? It may be your fuel sender unit (Under rear drivers seat) or fuel pump unit (Under rear passenger seat). Also, I'd check the fuel pump fuse at the rear fuse box in the trunk to make sure it isn't burnt/shorted.

cherishzm

Thanks for the reply!

Yes, electronics were still functioning properly but suddenly no power to the pedal. Since it died, it still cranks but no start. I did check the fuel pump fuse and it's still fine. Do I need to check the fuel pump relay as well? Not sure how to check it.

Is there only one fuel pump in the car? I bought the car last spring and did find records of fuel sending unit and fuel pump replaced by MB dealer about 11 months ago due to fuel sending unit leaking fuel onto fuel tank. I think it could be still covered under repair warranty if there's only one fuel pump / fuel sending unit and if indeed that's what failed.

gaazmon

MBZ calls them both sender units, but from what I know, the one behind the passenger is the actual "pump" and the one behind the driver is the sender. So from what I remember, the sender sends out the fuel to the engine and once that drivers side gets low, the level sensor will detect and advise the pump on the passenger side to send more fuel from that side of the fuel tank to the drivers side of the tank. They have different part numbers and look different.

Driver's side: https://www.autohausaz.com/pn/2094701394

Passenger side: https://www.autohausaz.com/pn/2094700294

Usually they have 12 months warranty. Not sure if it applies when ownership changes hands, but it should since factory MB warranties are transferrable.