hi guys, thank you in advance for reading/replaying to this. After a trip in the mountains, I stop the my 2000 ML 320, for few minutes, when I tried to start the engine...will not start, will turn, but not start( similar to when the battery is bad), few minutes later... it start. It happened again in the same day. I got home and went to check the battery at Autozone, in my way the engine dies in the middle of the street right close to Autozone.. after 5 minutes I got it star it.. Well long story short, the battery it's ok, and I suspect a fuel problem or ignition problem. I had the car for 1 1/2 years and I did not change the fuel pump or have no idea if it was changed. What I don't understand is why the engine will just stop when I'm driving, or why some times it's starts some times won't. I clean the fuel relay connectors and I'm wandering if I should change the relay...I can't tell if it's good or bad. Thank you again.

 

Very likely its the CPS.

 

You maybe right, I ordered the CPS, after checking the fuel pump. Thanks for your answer.